Guitar hero players (or at least, the subset of players in who are interested in very difficult tracks) are not trying to produce melodies or jamming harmoniously ; they're doing high speed, high precision pattern matching.
This is like berating gamers playing Elden Ring where they could do HEMA instead !
I'm going to have to say that this analogy doesn't work. The downsides of doing real HEMA are things like "you can experience what it's really like to have your head bashed in with a historically-accurate mace". The downsides of playing guitar in real life are things like "you need a guitar".
This is the embarrassing point where fun have been lost already but productivity is not there also.
Let people have fun.
This subject always reminds me of Squarepusher's Music for Robots [1], which was made to be played by robots instead of humans.
https://www.youtube.com/watch?v=k66nGplNRmQ
At least the Android Sisters play their own music:
Guitar Hero playes, on the other hand...
The Guitar Hero community is honestly pretty close knit, given the size of it relative to other more popular games. Some of my absolute best friends in the world I met through Guitar Hero.
Your dismissive statement has about as much cultural value as what you attribute to Guitar Hero.
At this point, the Guitar Hero community is its own subculture.