For pretty much the reasons many here have eloquently stated, I don’t think allowing an observer to delete comments on their observations is something the iNaturalist team is for, so that functionality won’t be implemented.
One possible compromise is the ability for the observer to hide a comment from their own view (others can see it), so they don’t have to look at it. But in the end, posting an observation to iNat is (in my mind) the start of a discussion with any other user on iNaturalist, and anyone can add an ID or comment that falls within the community guidelines. Discussions like that can get messy (although they shouldn’t be uncivil or mean-spirited), but that’s part of it, and I think if done correctly it can help us understand not only nature but the way we all view nature and science a bit differently.
If someone adds comments you don’t like or appreciate, you can message them and politely discuss that with them or even ask them to not comment on your observations.
It’s definitely a social network for people interested in nature (or at least the part of nature that involves sharing and discussing observations of organisms). I wouldn’t cal it “reviewed” in the strictest sense (like a scientific journal) but yes, observations are vetted at least by the community, and a recored of the discussion can be important for anyone wanting to use the data in that observation.