Tbf most of the adressed issues on GitHub are from older players - not many pilots just starting the game will push tickets on GitHub and I highly doubt the average player will make their concerns heard on GitHub. I am an IT student and could work with GitHub and similar sources and I personally do not think there is anything wrong with Linux for coding but Linux and gaming has been a shallow border topic for any game developer out there for multiple reasons:
If you got any issues with one distripution you do not know if it is cause of fault of your own or some side effects of used packages of the user (and there is a lot that can go wrong here as you should know). So it is an unrealistic ideal that Linux will be supported in a way that it will work without any problems on the user side - esp when considering the massive ammount of developer time that would be needed to achieve that goal for a small number of players. The market share is just not there - many bigger studios tried supporting Linux (look up the available games for Linux on Steam) and many stopped after a certain ammount time as the returns are just not there - why do you assume the calculus is different for CCP?. Accept reality.
On the other hand I do and used to engage with a lot of new players leading (FCing and other orga work) some of the fastest growing Alliances at that time (T.R.U had 2000+ members during the provi war from not existing at all). Evictus was a newbro friendly Alliance while I fced there (went from 1k members to 3k until it finally died this year) and Spectre Fleet npsi is the defenition of newbro friendly. Issues concerning these new players are by far more important than a potential non existtent Linux user baser that does not have a seperate gaming machine with another OS.
ESI issues are a double edged sword - whenever you were part of any bigger coalition that had the IT people that would put in the effort you had good tools at your finger tips - once leaving to a smaller entity some of these were not available to you. So the better ESI etc are the more it facilitates a support for exclusive access to your own peers and the bigger the gap between smaller and bigger entitiys. A good example for that would be the Jump Bridge Route calculaters that started poping up before it was implemented into the game itself. Legacy had access to tools that managed that Provibloc did not. Is this a good thing for the game? Debateable.
On another Hand you make it sound like the only Issues that matter are only to be found on GitHub - and that is just not true as laid out before: Many of the esp. newer pilots do not go to GitHub to complain - They complain on TeamSpeak/Discord or other normal ways of communication and I am convinced the majority of players do complain in these ways and a small minority would acutally try to get an issue resovled through GitHub etc. Touch Grass seriously.