Valheim [1] is one of an ever-increasing number of amazing games made by extremely small teams. It was initially made by one guy in his spare time, who later picked up a former coworker to come join him after getting quite far along. That game is arguably the single most technically challenging type of game to make: seamless and dynamic (time/weather/seasons) open world, player crafting/construction in a pseudo-voxel type system, multiplayer, dynamic skill based combat, and more. Even though I'm sure they've probably grown a bit since then, the overwhelming majority of everything was done by primarily 1 guy. So yeah, it's very possible to be a generalist.

Going in the other direction, the increasingly absurd size of companies is one thing I really just can't wrap my head around at all. The final output just doesn't seem to justify these massive teams and budgets when contrasted against vastly smaller projects, like Valheim.

[1] - https://store.steampowered.com/app/892970/Valheim/