There is still the gamer to QA pipeline, as hex debugging hasn't actually gone out of fashion. But it's nowhere near as prevalent as it was back in the 1990s, since that's how all "cheats" used to work for things like GameShark.

Server emulation is a whole other beast that requires a completely different skillset. It's not something that's as common to the average gamer today as modding was back in the day; seemed like every other Quake player new enough C# to make simple conversion mods, and it seemed like every other TEN session was running some custom Quake server mod, like Quake Cars or whatever.