Actually, I think they don’t want linux gamers, with their higher technical savvy. Some game dev companies love how 90% of their bug reports come from 10% of their users (and even brag about it). Other companies would rather just not get those 90% of bug reports.
The article I had found on the topic suggested linux users provided higher quality bug reports, in addition to more bug reports.
The real issue is that some game companies don’t want bug reports because they don’t want to fix bugs.