When your Linux distro doesn't play nice with some hardware and your open-source solution goes boink! who do you, the naive computer user without ten years experience of coding and Linux kernel hacking go for support?
The Linux SysAdmin(s) that you hire who are almost always significantly more skilled in all things computing than the massive throngs who throw down cash for MS cents in the hopes of getting a paycheck, but who have little actual passion for the technology?
If you can find a competent Linux Admin who doesn’t spend significant portions of their own free time furthering their own knowledge then you may have spotted a unicorn. For a Linux problem, there are also far more people with access to the solution, it’s not controlled by a single entity from their support line.
It’s not like getting support for a Microsoft issue is easy. I’ve spent hours and hours on the phone as the script-reading phone monkey exhausted went down his list before declaring defeat. They are no more legally responsible to solve your problem than some random Linux guy. This notion of ‘reliable support’ is a myth. I doubt it happens any more or less often than any other platform. You’re always at the mercy of someone who may or may not tell you to go crap in your hat.
These are the people you want your business to depend on?