This is a dumb argument. Yes, my phone uses Linux. How many of the Android users actively come in contact with the underlying system?
Mainstream Linux means a big part of people actively choosing to install a Linux distribution or buy a computer or notebook with a real Linux distro pre installed (not that lightweight barebones distro they preinstall so they can sell it without Windows but with OS).
I use Gentoo, the family PC has OpenSUSE, only my wife’s laptop has Windows… Because guess what, she wants to use what she’s used to, what she knows.
Also the dumb system that thinks it knows what you want to search and no exact term search feature. Yeah, the search is unusable.