Take a look at this Feature Request a while back. It addresses your subject and there is some discussion about the pros and cons of such an approach.
That topic led to this follow-up Feature request which in turn expanded the discussion.
The discussion led to @upupa-epops creating this Mangroves of the World paraphyletic project.
It’s certainly being done, but it’s a bit tricky to do so within the structure of iNat.