Sure, but almost nobody uses or wants modern linuxes on those machines. It's almost always described (in their own words) as "some ancient crusty version of Debian"
> Nobody wants to play games on Linux given the small userbase compared to Windows.
According to the last Steam survey, 3% of players use Linux. Steam has 130 million active players, so that means there are 4 million people playing on Linux. Definitely not "nobody", and way bigger than the whole retrocomputing community.
By the way, I am also one of those retrocomputing guys, I have a Pentium 2 running Windows 98 right here. IMHO, trying to shoehorn modern software on old hardware is ridiculous, the whole point of retro hardware is using retro software.