I've worked in the video game industry for a couple years and have been credited in several games. This number may actually be higher.

It may sound crazy, but there's a lot of people working on AAA games, usually most of them completely unrelated to game dev. Marketing, public relations, translators, 3D graphics artists, sound designers, orchestra performers, motion capture stuntmen, voice actors. Probably a few dozen managers, who have never even seen the game. Hell, some companies even credit IT staff in the game's credits.

That's already a whole bunch of teams. It's also important to mention that many third-party contractors will often be skipped from the credits. QA is very commonly outsourced (to poorer countries like Romania or Serbia) and rarely gets into the credits. You may only see 5-10 names, while in reality it was at least 100. This is true for several other fields, though mostly non-game-related, e.g., localization, promotial material, merchandise.

I won't disclose in what capacity, but in the past I have worked on several of Blizzard's titles for a few months and I'm not credited anywhere. Just like at least a couple hundred other people. Not necessarily saying I should be - it was never mentioned or promised. Just highlighting that the real number of staff that worked on the game (or adjacent to the game) may be above 10k.

Yea there's still ongoing seasons for Diablo 3, Diablo immortal, Diablo 4 (seasons and another expansion), Diablo 2 resurrection. Probably other stuff I'm not aware of.

Crazy that AAA games take that many developers no wonder they all feel a bit samey.