mint, based on ubuntu, has been placed on many computers by me, for people with zero awareness of command line.
I now have significantly less work to do to assist these people, they literally never get malware anymore, and things just work.
so while that may be the argument used against linux, i'm guessing the complicity against it is more mainstream propaganda than truth.
linux is much closer to a user friendly interface than many are led to believe, and it is in fact the computer manufacturers that are adding a level of difficulty with lockdowns in the bios (lenovo is the worst..) and other attempts to make it more difficult. pretty much every new laptop refuses to load either the ethernet or wifi chipset on release...
anyway, i hear you, I'm just not convinced the reasons are valid, it is more of lack of interest perpetuated by propaganda. and fear... dear God fear. if you've never talked to an IT professional about linux... they are clueless ignorance there.. they have been brought up on windows, which does not mirror real life computer maintaince, it becomes knowing the ridiculousness that is windows more than truly understand the inner workings (you can't know the inner workings of windows... )
so really we have a huge problem of education in the negative sense, people are trained to know windows and fear anything else.
I have used various forms of linux for over 10 years and actually created a UNIX command line compiler during my applied computing degree so I have a pretty good understanding of what's involved with the OS variants. I currently use Fedora as it is a balance between enterprise grade software and user grade.
it would not take a huge amount to boost linux enough to overtake windows, but currently it involves a degree of organisation and maybe unification that hasn't been present yet. there are also issues with larger companies doing licensing deals with microsoft etc. - but this may become less relevant the more advanced linux becomes.
what will help the most is open source hardware schematics that can be replicated with 3d printers etc.