OK, first, I will say that I agree that D&D probably has too many spells, or at least too many spells that basically do the same thing. I personally prefer the simplicity of something like Savage Worlds where there's a
bolt spell and you, the caster, basically decide if you're shooting firebolts, icicles, shards of holy light, swarms of angry bees, or something else--the spell works the same regardless, but the trappings are different, and you can buy power modifiers to say that the firebolt also sets someone on fire so they take damage the next round.
I would have no problem if they combined a lot of spells the way they combined
Bigby's hand and either reduced the spell count considerably or replaced the spells with ones that did very different things. Like, turn all your 3rd/4th-level area-effect mass-damage spells into one spell but replace them with a spell that turned smoke or clouds into a malleable substance you could create ladders or bridges out of (there were two or three spells like this back in 2e).
I think that there is some truth in that, though it seems to be an unproveable assumption and people likely know of dragons and orcs from things other than D&D, but you could extend that argument throughout the entire gamut of the TTRPG industry and just say that people must know X or Y because of D&D. However, I'm not sure if that means that D&D must necessarily have longer spell/monster write-ups and more detailed descriptions or even a greater quantity of spells/monsters or that these other games aren't making conscientious design choices with writing their books more concisely.
I don't think that D&D monsters necessarily
needs longer write-ups. I'm just saying that a lot of designers are thinking "everyone knows what an orc is" and therefore don't feel the need to spend a ton of text describing them. As an example, the Savage Worlds Adventure Edition Fantasy Companion lists kobolds as "small dragonfolk" and mentions they use traps and ambushes--all D&D things (this certainly has little to do with real-world stories about kobolds). They don't
need to spend many pages describing kobold culture because the book is covertly saying "look at D&D for that info!"
If the SWADE kobold was more like the
mythical one, it would very likely have a much longer description.
Likewise, you say that Black Hack has like two pages of spells. But that's because those are all D&D spells. First, look at Charm
Charm : A Nearby target obeys commands. Test WIS each turn to see if the effect lasts.
Whereas the 5e version is split into two spells (plus all the other spells that charm targets--IMO, the Black Hack spell is more like
dominate person than
charm person) and has a linked condition. OK, But... if I'm playing Black Hack and use this spell to order a target to kill themselves, will they? There's no answer--not even a "Test Wis if given an order that is self-harmful or goes against their moral code," which means that the game has a good chance of screeching to a halt while the DM and players argue about the result. And considering how much people talk about these things online (or in the pages of Dragon Magazine), this
is something that can and will happen in a game where it's not spelled out.
The Black Hack version certainly isn't
bad by any stretch of the means, but it also doesn't take into consideration the knowledge that has been accrued over nearly 50 years of playing D&D (and it doesn't have tournament play like D&D used to have), which is why the D&D version is longer and more in-depth.
Next, look at Animate Dead, which is a very long D&D spell.
Animate Dead : Create 2d4 Skeletons/Zombies with HD/level, from nearby bodies.
Now, I managed to find a scan online of the original D&D books from '74. Here's their
animate dead from Vol 1: Men & Magic:
Animate Dead: The creation of animated skeletons or zombies. It in no way brings a creature back to life. For the number of dead animated simply roll one die for every level above the 8th the Magic-User is, thus a "Sorcerer" gets one die or from 1-6 animated dead. Note that the skeletons or dead bodies must be available in order to animate them. The spell lasts until dispelled or the animated dead are done away with.
Barely any longer, and most of the additional length is due to Gygaxian verbosity, using 15 words to say what Black Hack says with "from nearby bodies." The man really needed a course on conciseness in writing.
And then you compare it to that spell in further editions of D&D and it gets progressively longer.
But why does it get progressively longer? For most of it, it's because over time, the players and designers realized that it could be super-powerful because a relatively low-level player character could get their hands on a permanent, malicious army of undead (nothing in either version above that says the zombies won't go out and do zombie things on their own). And that's not what they wanted for the game--at least not for 5th level PCs. So that's why the spell's description increased as time passed, first to limit how many undead you could control at a time, and now to limit the undead's actions to what you command them to do rather than implicitly allow them to wander off and do things on their own.
