Edgy, in vanilla it was a good diablo 2 clone.
But vanilla WoW has pretty much nothing from Diablo 2 in it, unless all you knew from the two games is "they both have RPG elements and are perceived as grindy".
Diablo 2 has an end goal you can achieve by playing solo. WoW's end-game is pretty much entirely tied to group content, be it raids or battlegrounds, and even then, there's no real end goal.
Diablo 2 doesn't force you, at any point, to grind for anything - you can beat the game with self-found items and as a single-pass character, if you have the persistence and skill. It's just that the game's ultimate items are gated behind a sizable wall of loot-grind, but you don't need these items to complete everything there is to see. Even Uber Tristram can be beaten with a build that primarily relies on stuff that drops from the
Normal difficulty.
In Diablo 2, an item you find at level 24 can serve you the entire game due to unique properties, especially as you can upgrade weapons and armor through Horadric Cube crafting, so low level items like Bonesnap, Ribcracker or Steeldriver can potentially carry you throughout the entire game. In WoW, you're calculated to be replacing items every few levels, and most new items you receive are improvements in terms of numbers; you'll scarcely find items that may
drastically change the way your class plays.
The way Diablo 2's ladder seasons work is completely different from the "seasons" in WoW, which are basically a way to gradually gate content for the players.
Diablo 2 doesn't ever force the tank/healer/damage trifecta - every character is self-sufficient in terms of survival, sustainability, or damage.
Diablo 2 doesn't have Soulbound items, and although Blizzard initially did not support the practice of muling, it is nevertheless possible to transfer items between characters or freely trade them to other players on b.net. In WoW, the only items you can trade or keep for an alt are specifically BoEs.