It's older than that. But under JPII and Benedict, the traditionals were mostly aligned with church leadership and not very vocal. Benedict wanted to fully bring them back into the fold of catholic mainstream, and that basically created the phenomenon because it meant that they got a lot of attention and were able to recruit/get into important bishop positions. Benedict chose bishops mainly based on their views on sexual morals, which empowered the traditionalists even more.

The biggest push in public definitely happened under Francis when more traditionally oriented mainstreamers switched to "oh, I'm a trad-cath".