How exactly would a new Linux user know this ?

What happens when they install Ubuntu and the Wifi doesn't even work ? An experienced Linux user might figure it out.

A new user would, very reasonably, assume Linux doesn't work and reinstall Windows.

> How exactly would a new Linux user know this ?

It's easy: whatever is preinstalled will be guaranteed to work reliably. Worked for me.

So sticking with Windows because that's what the computer probably shipped with ?

No, buying preinstalled Linux.