I can't recall the name of the project, but I worked with some guys moving from DITA to a different engine. I don't like DITA at all, but I didn't like the tools I had available at that time. (I don't like HTTP/XML/JSON/TeX/PostScript as a format for expressing document patterns without serious heavy lifting from a GUI.) I do recall that a lot of people kept asking "Why?" though which implies quite a lot of fans of DITA even within that relatively small community.
As for OASIS, I've used some of their JSON related stuff enough that I tried to influence the evolution. You can pretty much just think of them as "yet another standards body" motivated by "do all the internet things". They do seem though as having more of a fetish for XML than other standards bodies.
The "other engine" was, unbelievably, a flavor of wiki. I liked it a lot better, even without a GUI, because it had crazy fantastic support for "here documents".
Say, for example, you needed a table:
Yep, you could just use CSV if you wanted without specifically marking up columns/rows.
I loved that a little more than is honestly reasonable.