I think it's more that devs see Linux support as a liability. Linux market share is low, and supporting Linux opens them up to Linux specific cheats, so they'll need to spend resources on Linux specific mitigations. Why do all that for ~2% market share, most of whom seem content not playing their games?

I don't think we need to jump to conspiracy theories. If Linux adoption gets to 10% or so and still see this issue maybe the conspiracy theory carries some weight.