Hi, so I've personally been very involved in not nerfing her. Here's why:
We're in one of the more diverse metagames right now. Outside of specific points in time, (Ashe Support until 13.5, Lucian during 13.1, Caitlyn during 13.3, Annie during 13.4) there haven't been any bot laners over 80% presence. That's really good. Compared to some previous tournaments, we have about as many bot laners (ADCs) with 10%+ presence on every single patch as Worlds had last year, which was generally regarded as a high point for diversity. We have had no 100% pick/ban ADCs at any point either, which also trumps MSI 2022. So while Zeri has been a fixture of bottom lane for sure, she's almost never been the dominant option and has never been so strong that both teams vie for her every game. That said, she has finally crossed 80% for the first time during 13.5.
I'm pretty against playing whack-a-mole with the pro meta during the regular season. Two primary reasons:
We get to see players shift priorities as time goes on. This is pretty evident with the rise of champions like Gragas despite no changes and other priorities across roles. Turns out we're not really in a marksman support meta, it's just that people played Caitlyn and Kalista there once in a while. With no changes, Karma has dropped off heavily in priority. Why was Xayah sitting at 10% presence across all of 13.1, 13.1b, and 13.3? Why did it take until 13.4 for pro players to realize she was so strong?
It also risks creating one of those 100% presence champions out of thin air. There's no Varus complaint right now, but there were times he was the obvious #2. What happens if Zeri got nerfed in those patches? Is he just the automatic go-to?
Right now, a lot of ADCs have really close presence outside of Zeri. For the first time, she actually stands far above the rest of the crew and is thus a reasonable nerf candidate. But this is, IMO, the first patch of pro play where it's made sense to nerf her. And even still, 13.6 nerfed her most common pro builds: Lethal Tempo, Quickblades (61% pickrate), and Bloodthirster (45% pickrate) are all nerfed. So even then the question is, "Will pros change their behavior at all in the face of three direct nerfs?" I'm betting no.