Did you read the article? One of their really own says they are to blame for the hellscape!

Valve’s implementation of its in-game stores and the Steam marketplace, Varoufakis says, emerged from a need to balance monetization with a fear that if the company didn’t create its own systems for exchange between players, they would “take it outside”

They are a for profit company, they most likely support linux so that people don’t “take it outside” their useless proprietary launcher.

Factorio is proprietary software, Mindustry isn’t