I’m in two minds about these apps. I’ve tried Plant.id on two species, but I am much happier trying to work things out for myself. However, I can see their usefulness in some circumstances.
Part of the problem is that there’s no way to know if the algorithm has arrived at the correct answer. At least with iSpot and its “competitors”, the agreement system provides some indication of the reliability of the identification.
As to the effect of their proliferation on iSpot, I agree that it could be even more damaging than the disastrous re-coding that has driven many users away (and the various problems seem to be here to stay).