The fact that it does not work out of the box is already a bug, why not open an issue on linux mint instead of endlessly trying to tweak things? (possibly a problem of unrealistic perfectionism tbh).
Linux is already mainstream (according to statcounter 1 in 25 people in the US use Linux). but hardware can be a problem and if you don’t check if your hardware is supported (or probably even better buying hardware that officially supports linux) there is a risk there will be problems.
With that said use what works, you are getting this for free and nobody owes you anything.
Yeah it was said by email, i actually did some research and turned out it is indeed not legally binding, i think it is good to know.