To be fair, for flowering plants at least, a quick filter on “please add” or “missing” shows that many, if not most, of the unresolved requests to add taxa have multiple comments on them, suggesting that those particular requests were not simple or uncontroversial.
Such flags certainly need to be re-visited periodically to see if there can be further progress. But given the large number of pending flags, it may be a situation where “the squeaky wheel gets the grease” (e.g., the original flagger adds a comment to spur further action). Not ideal, but possibly the best we can do. Still better imo than the curatorial work created by continuing to allow external imports from obsolete sources.
This is a sound analysis of an iNat problem: there is a lack of active curators who can do the basic flag requests such as adding new species.
Instead of waiting for new curators to apply, iNat may consider to invite possible new curators by reviewing the users who have put up a certain number of flags concerning taxon additions or changes. This may be some effort initially but long term would help.
(and yes - do away with curators who have never done any curator tasks)
Given that when applying to be a curator, one must include an example of a taxonomic change one wants to make, would it suffice to frame it in terms of existing flags that one wants to resolve?