I can't second these experiences. Ubuntu became popular pretty quickly it just haven't been able to retain users. After Mac OS X and then iOS it was likely that the Linux kernel could be the basis for a smart phone, just not most of everything else. And that is also what happened with Android.

What has been said is that the Linux desktop doesn't have enough applications. It doesn't have the most popular and capable packages for engineering or creative work. And that is still true. Desktop operating systems are now more and more of a niche so those who do run them often want to do a verity of things.