With "sex-focused fests" you mean hd_tropes and hd_clichee? I am not even sure whether this is true but I have no hard facts as to the number of explicit fics in Tropes and Clichee.

I do continue to read predominantly R and NC-17-rated fics. And I will admit that a lower rated fic has to really grab me so I enjoy it (sorry, sorry, sorry, all you gen writers). However, I also have entirely stopped to read sex scenes that feel tagged on and superfluous. It has become a back-button issue for me.