I say this half jokingly but I've always had the suspicion that a lot of this performance talk from gamers is akin to pretentious New York art snob-types bs'ing about fine art. Maybe I'm just a dullard for these things since I primarily play single player games on outdated hardware (finally built a new PC last year though to catch up a bit) but I'll never not be at least a little skeptical and suspicious.
On a certain level, yes, there is definitely a snobbish attitude when it comes to gaming performance, particularly from the hardcore PC crowd.
However, on a base level, performance metrics such as input latency, minimum acceptable level of frame rate and/or frame time, FOV, and server netcode and tickrates can be big issues that affect different people in different ways, and can vary depending on type of games played or even what level of performance you have been used to in the past.
In Stadia's case, input latency has been reportedly bad enough to warrant legitimate issues, particularly in fast paced action games such as multiplayer shooters.
Also, Stadia's advertised level of performance is....well, apparently a lie in most cases.
