The issue isn't using it, it's getting it set up, working with all hardware, getting everything that's needed installed across different repositories, configuring everything the way it's needed, then keeping it running, survive updates, and fixing it when it breaks, which desktop Linux is still very prone to (apt dependency conflicts have wrecked beyond repair many Linux installs I've run).

At some point, you have to have a pretty deep understanding of how Linux and computers work to Google the right things, and then understand and apply a fix – or worse, you may have to work out one on your own, which may entail things like reading source code and patching stuff; I'd say I'm somewhat competent as far as running Linux goes, and I've had numerous issues over the years that I was unable to fix, mundane but non-negotiable things like "getting sound to work". Best case, that'll just require more or less heavy command line usage, which only a tiny minority of people have ever used before and which is highly non-intuitive at first.

That amounts to building a very comprehensive set of skills that is completely worthless to most people otherwise, and that you don't need for Windows or macOS, let alone Android/iOS.