I have put my dad on Kubuntu. Don't like anything *buntu, personally, but I have to admit it's quite stable and with sane defaults. He hasn't complained ever since and support calls dropped considerably. He spends most of the time in Firefox anyways, where I've added ublock.

The problem with Windows was, he'd occasionally browse the web with Edge by mistake (or because MS forces it down your throat), and as soon as an 80+ y.o. browses the web without ad blocking, getting a virus is just a matter of time.

All this is to say that I agree with the fact that preinstalled is key. I wish that more effort was focused on fewer distros and I feel that so much talent and energies are being lost in marginal projects.

But many people do this for passion and it's of course their choice to decide where to contribute, or whether to spin up a brand new distro entirely, can't judge them for that. I'm just observing that those energies could be better used to smoothen some rough edges on more popular distros to make them even more appealing to OEMs and convince them to ship those on their hardware.