Yeah I was a Gnome user until Gnome 3. That was so unusable I switched to xfce and later Mate. There insistence on that big bloated touch screen interface on a primarily desktop UI was so stupid and cost them users.
Now not enough people care if they stick around to fund them.
It means removal of 1/10th. deci 1/10 matus remove. So yes decimation was the name of the Roman punishment where 1/10 of a group was killed. But it can be applied to any group of people or things.