well I can answer that directly..
I have games on steam that haven't operated since windows Vista/7 (at a push), however I recently switched to Linux and it turns out that they "just work", no fiddling required. Double click and play (proton is gold)
As steam have delivered to me the game I paid for, the fact that I previously didn't have the right OS is not their problem. Their part of the agreement is complete, and I am a happy consumer.
I know I don't 'own' any of the games and if Valve shut down tomorrow I would lose access to them, an issue I'm not that arsed about as they are just games and piracy is easy.
Used to be a thing with O2 here in the UK. My iPhone 3G (so, 2009?) was affected so I had to install an app that allowed me to tether.