Their innovation isn't in ads, it's in creating a sticky app experience that downranks posts with external URLs to keep people on their site, one that's now fine-tuned to retain the lowest-common denominator of technology user (boomers). Ironically, a segment that the OG Facebook avoided like the plague is now their bread and butter.
People who don't understand nor care about how the system works are the ones most likely to click on targeted ads, share sensationalist slop and comment positively on AI videos of of Hegseth fighting Godzilla.
And even then, for ad buyers, the ROI is a complete crapshoot because of how purchase attribution works on every ads platform. Every ad platform puts their marketing pixel on your site, and they all try to take credit for every sale made on it.