I'm not saying that people don't have good experiences with Linux desktops. I'm saying that those experiences are still nowhere near universal, especially when you start to involve people who aren't really power users. The most common desktop environments are still wildly inconsistent at best and frequently an accessibility nightmare at worst. Trying to work out whether a given piece of hardware will be well supported (or supported at all!) is difficult. Resolving package manager conflicts, handling non-free firmwares, building and managing kernel modules, these things are _not trivial_. That's before we've even addressed the software that people are often forced to give up. I use a Linux desktop frequently and there are papercuts _everywhere_.
I'm really not sure where this prevailing mentality that you can just install Linux and ride off into the sunset comes from.