I never said they had to. They don't have to support it or any machine.
However, that doesn't change that there are problems that can be attributed to Linux. For example, sleep/wake's incompatibility with the "Modern Standby" is a Linux problem that affects a wide variety of laptops.
It also doesn't change that it is tiresome when people come on to internet threads and say "I've had no problems - you must have exotic hardware!" We don't have exotic hardware - Linux just doesn't support certain common-enough hardware well. That doesn't necessarily mean Linux is to blame for it, but don't blame the user's "exotic setup."
Edit: On the contrary, it's often the people who say they have no problems who have the real exotic hardware - because they bought System76 or Purism or an XPS or something designed to be Linux-friendly.