Of course not - if Xfce has too few people working on it, MATE has even less than them, and Enlightenment has even less than MATE. And note that Enlightenment is not only the desktop environment per se but the E libraries (and those are no regurgitated shit - for example, some car makers have used them on their infotainment systems). I'd think it'd be amazing if those two (or those three) could do a Dragon-ball-z kind of fusion, I think those three have really similar goals. Hell, if that was actually a thing most probably I'd move to that.
I know Xfce folks have submitted patches to GTK over the years, but it's just that GNOME's enshittification has pregnated GTK to a point of no return and Xfce devs are very well aware of that (for example, the libadwaita thing).
No, but I want to be one.