Because they’re basically the same thing
I grew up in a hippy-ass new-age household where a bunch of middle-aged white ladies would come over every week, sip herbal tea, and swap tips about practicing appropriated Indigenous American spiritualities. I mostly failed to internalize anything my mom’s friends talked about, since it was very boring and they always smelled like old bong water.
The one thing that penetrated my apathy and disdain—besides the time one of them dosed me with LSD at age 11 because they thought it would be funny—was astrology. I didn’t have any particular reverence for the stars, but it was an excuse for me, a self-absorbed “gifted” kid, to think and talk about myself a whole lot. Astrology gave my childish egotism the trappings of mysticism and divinity, which was really neat.
Of course astrology isn’t real, but neither is anime, wrestling, video games, or Dungeons & Dragons. Things don’t have to be factual or tangibly magical to be fun, so let’s get metaphysical.
When you get down to it, horoscopes are all about stereotypes and sweeping generalizations that create the illusion of plausible fortunetelling. Similarly, D&D classes give you a vague archetype and a pile of fun, magical weapons of mass destruction that create the illusion of a coherent character. So, why not combine the two?
Hey dork, you picked the most mechanically intricate class in the game. But you knew that, right? You looked at the huge section of the rulebook dedicated to spells and you wanted an excuse to read the whole damn thing. Your class is either amazingly powerful or completely useless depending on preparation and your ability to read the room. Good luck Capricorn, you’re going to need it to survive the early levels.
You’re full of that intuitive, bullshit future energy huh? Your spells take no preparation at all, and since charisma is your spellcasting stat, people gravitate to you just for being good at magic. Capricorn, the virgin wizard, spends hours agonizing over which spells to prepare. But you, the chad sorcerer, just empower and maximize chain lightning or fireball and utterly destroy the party’s problems. Sometimes you make enemies by exploding everything, and sometimes you run out of magic juice and have to hide behind the fighter for a while. But you’ll be back in no time, Aquarius, making it all look frustratingly easy.
Good news, Pisces. You’re pretty solid at everything! No one can get mad at you for picking the wrong class, since you basically picked all of them. Plus, with your high charisma and optimized diplomacy skill, you can roll that d20 and make people like you.
Hell yeah, Aries. You pumped up your strength to 20 as soon as possible and break every combat encounter just by being in it. You’re frustratingly hard to kill, and difficult to engage with politics, arcane mysteries, or any other bullshit you can’t solve with horrifically, impressively brutal violence.
You were willing to play whatever class the party needed most, so now you’re a cleric I guess! No matter which god you pledge your service to, your main tool is the spell Cure Wounds, so keep that d8 ready. You’re constantly trying to balance your god’s ethical demands against loyalty to your terrifying murderer friends in the adventuring party. It’s tough, Taurus, but you’re built Ford tough.
You’re a fucked-up wizard and your dad is Satan, right? That basically makes you Raven from Teen Titans. Everyone who watched that show had a huge crush on her, so you’ve got that going for you. You can use nonsense Yu Yu Hakusho spirit weapons or have an evil ferret from space if you feel like your main gimmick isn’t enough. But trust me, Gemini, your backstory is complicated enough already. Maybe stow the ferret for a few sessions.
If your game didn’t have Tolkienesque “nature vs. the machine” themes before you picked your class, they’re getting shoehorned in now, Cancer. You hang out with a group of mercenary killers and tomb robbers, and your primary concern is their carbon footprint. As a druid, you get to be part of something bigger without having to conform to any societal expectations or put work into a relationship. That’s pretty rad, but you’re going to have to try extra hard to stay relevant when the party lingers in the city of Waterdeep for two months of your real life.
Did you think you were going to be the Bard, Leo? Nothing is more vainglorious han a lawful-good paladin, and you live to bring your obtusely black and white morality into every. Single. Scene. You get to be inarguably morally good while also using the power of justice to rack up an impressive body count. You’re an asshole, but ultimately a good friend when the party needs you.
“Rogues do it from behind” sayeth the ancient meme. Now, in the year of our lord 2019, I’m going to take umbrage with a joke mostly found on decade-old nerdy tees. Rogues are the truest switches. You’re able to control the flow of the game if you want to be a kleptomaniac or compulsively kill people because you can, but you can just as easily enter doormat mode. Your sneaky scouting and locked-door-opening prowess make you useful to the party, and that feels nice. But there’s a middle ground between being a human lockpick and turning your game into the Virgo show.
You believe in the interconnectedness of all things, and you express this belief mostly by beating the everloving shit out of anyone or anything that gets in your way. You make a big show of avoiding conflict, but when a quest goes south and you end up having to murder your way out of your current predicament, you’re clearly having as much fun as the barbarian. Your friends can tell by the vivid, grisly way you just described punching that orc in the throat.
Fighters aren’t given much of a compass beyond “I sure am good at fighting”, which is lucky since fighting is most of what you do in D&D. You’re empowered to act, and given the freedom to decide why. Your ability to lead the party forward without getting obliterated by a fireball trap makes you an ideal leader, and not having pledged your soul to a jealous light god or a nasty-ass demon often makes your vote the deciding voice in party conflicts. Your friend group is a clown car full of forbidden magicks, misused divine power, and daddy issues, but you’ll get them through the dungeon alive somehow, Scorpio.
D&D is about power fantasies. Barbarians are superhumanly strong, Bards are sex gods, and Wizards can cast a spell that makes you giggle uncontrollably for like 20 minutes. You, Sagittarius, get to indulge in the fantasy of running away to the woods, making friends with a grizzly bear, and never really coming back. You don’t get attached to places easily, which is great for D&D, since there’s always a 50/50 chance your friends are going to burn any given town to cinders because they couldn’t talk the local blacksmith into giving them a discount. But no matter how self-reliant you are, you’re going to need to open up to your party eventually. You’re at a table playing one game with a bunch of other people, and that structure doesn’t really leave much room for loners.