I still feel a bit sad about the changes that happened ~2012. Linux on the desktop really had a strong momentum going around Ubuntu and Gnome 2, where quite a few non-geeks started switching over as well. But then everything fragmented quite rapidly – Gnome Shell was quite unpopular on launch, Ubuntu went in their own direction with Unity, Mint went in a different direction with MATE and Cinnamon, Elementary forked off Pantheon, etc. Similarly, RedHat pushed for Wayland and Flatpack while Canonical pushed for Mir and Snap, and so on.

I'm not saying that Ubuntu/Gnome was everything Linux had to offer (I myself was on Arch and i3wm at the time), but that period was certainly when the largest percentage of people around me were enthusiastically adopting the Linux desktop.