This strikes me as quite a drastic ‘overkill’ solution to the problem of the Agree button. If it was implemented it might lead me to completely stop using iNat.
Overzealous agreement is definitely a problem, but this suggestion would interfere with far more than just that. The first issue is simply that it puts way too much emphasis on the importance of research grade. That’s not what iNat is for! It’s to get people to engage with nature. If a person makes their first observation hoping to find out what species they saw, and the site deliberately hides that information from them, it’s the opposite of encouragement.
There are also practical reasons why it’s really useful to be able to see others’ species-level IDs. The most obvious is that in some taxa and places, there are so few identifiers that a single ID might be the best that an observation ever gets. Even good and theoretically identifiable observations just don’t always get to research grade. Such an observation would be ‘trapped’ at genus level forever, even after a dedicated identifier might have put the work in to be specific. Or perhaps more likely (and more unfortunate), identifiers in obscure taxa might lose interest or give up, if their efforts are likely to be kept invisible - and similarly, observers might stop bothering if they know there aren’t enough identifiers to be sure of hitting research grade.
Even in the context of observations which will eventually reach research grade, there are serious downsides to this suggestion. Seeing what species someone else has suggested can be really useful for making an identification of your own! A genus might have hundreds of species in it, and for a non-expert that may be discouraging or impossible to narrow down further. But with a suggested species to start from, it’s possible to research identifying features, native range etc, and come to a conclusion about whether it is (or isn’t) that species.
I’ve described all these downsides, but I also just realised that there’s a very obvious workaround. Identifiers would simply be able to write their species ID into the comment box. This would be an annoyance and an extra effort every time, but would also invalidate this feature - everybody loses! The end result would effectively just be that there is no Agree button on species-level IDs, which is a much less drastic suggestion that’s already being discussed elsewhere.