There are a lot of factual errors in your post
I would appreciate you pointing them out. I obviously have opinions, but I am trying to present a veracious narrative here. Some things I cannot know but I have tried to be clear when I am speculating.
I’m not sure quite sure which changes you’re referring to when you say “so many changes”. Many, many taxon changes have been committed since iNat began switching to POWO in 2018. Our taxonomy has definitely not been static since then. Annual novelties in IPNI create work for POWO and WFO, but not necessarily for us. Staff has been explicit about not adding names to our taxonomy unless they are necessary to ID observations, so most of that does not affect us.
I don’t think the volume of novelties are directly germane to the site policy changes on vascular plant curation that have been made over the past year or so. Rather, some of the plant taxa that have an unknown relationship were left there because curators looked at the literature, saw it was not clear whether to deviate or match POWO, and left them alone. So the backlog continues to grow, which staff do not think is sustainable. More recently there have been some high-energy attempts to resolve taxa lacking taxon relationships without background research. Sometimes this cleans up things that should have been synonymized but often it is discovered that POWO ought to recognize that taxon, but only after it has been lumped and lost in a bigger pool of observations. That’s generated a lot of drama reaching from our flagging system to staff email. The policy changes have been an effort to strike a balance between these forces.
Ferns are a bit of an odd case, which I can speak to because I did the bulk of curatorial work on them until a few years ago. When taxon frameworks and POWO alignment rolled out a few years ago, ferns were not ready in POWO, and with the encouragment of staff, I started aligning genera with the 2016 publication of the Pteridophyte Phylogeny Group, PPG I. I did this in a fairly conservative fashion: there were some changes I didn’t make, like Osmunda claytoniana to Claytosmunda claytoniana because it would involve many observations and I wasn’t sure the splitting of Osmunda would endure, and several genera where the New Zealand Flora and PPG I circumscriptions differed, the former having been used as a basis for our taxonomy early on. So ferns are in a weird space where they’re under the POWO taxonomic framework but there are a large number of deviations, generally one-to-one (species circumscription is the same but genera are different).
I am trying to get us switched to WFO for ferns and lycophytes, where PPG is now the TEN, but have not heard back from staff as of late (World Plants is in pretty close sync with this as well). I think wanting fewer genera is a defensible desire (and PPG II has done some lumping, particularly in Microsoroideae) but if new names are neither published in those genera nor recombined into them, then the system is not being maintained and is not very useful.