ARPG aka Action Role Playing Game.
tl;dr - Diablo or Dark Souls?
Both Diablo-likes and Souls-likes are called Action RPGs. In one, you create a "build" using gear and skills, and generally grind for hours on end looking for the perfect drop to make your build a teeny bit better. In the other, your success is based off of twitch reflexes and learning move-sets of the enemies. Gear and loot is pretty downplayed and the enjoyment comes from the elusive "git gud".
I'm not here to argue that one or the other isn't an ARPG. I'm just curious why a new designation hasn't sprouted up for one or the other to make things less confusing. It's getting even worse now that Diablo-like games aren't limited to isometric POV (they haven't been for a while but...) and now people are making souls-iike games in isometric POV. It's only natural that this would happen. But again, why is there still the confusing naming convention?
IMHO, worthless though it is, I don't get why Diablo-likes are called ARPG's. They have lots of A and no RP. (They are Gs tho.) Souls-like feel a lot more like what I would consider an ARPG. But again, my opinion is completely worthless so it's pointless to even attempt to argue about it.
My point is we should riot with pitchforks and torches at the headquarters of... the people who name genres of games... and demand they split ARPG from ARPG so we all know what we're getting into.
Like, someone went ahead and invented "bullet heaven" as a genre name since "bullet hell" didn't quite fit when you were the one with the bullets. I love that! Maybe we can do something similar like call Diablo-likes Action Grinding Games (AGG) or Loot and Build Games (LBG). I'm sure someone can think of something better while we are marching.
I think ARPG is just broader than that. Bethesda games are also described as action RPGs, yet they are neither really about builds or gitting good, it's more of an exploration / virtual theme park thing.
I think the definition of an ARPG is "an RPG where the player's skill in controlling the character in an action-game like fashion has a major role in gameplay, as opposed to games where the character stats or strategy is solely decisive", like in Divinity or most older RPGs.
It's like when people describe both Doom and Six Days in Fallujah as an FPS, yet they are nothing alike.