There is a third reason for a “blind” Agreement.
As a user from iSpot with a reputation system, when we moved our data from iSpot to iNat a lot of our identifications changes because of the absence of a reputation system on iNat.
So for instance, taking the genus Drimia that only three people on earth can really identify accurately (no field guides, difficult characters, etc.), on iSpot two of these people (the third did not join the site, but is now on iNaturalist) did most of the IDs and their Expert reputation sealed the ID.
This did not work when the data were transferred to iNaturalist, and so to ensure that the correct ID was the “Community ID”, we had a team agreeing to our expert’s IDs just to ensure that the most likely ID (by far) was the community ID.
Alas, it has stuck. When I see an ID by a taxonomic expert or by a high reputation amateur I simply agree. On iSpot I would never have done this because of my reputation. But on iNat I dont have a reputation so it does not matter that I agree without going to the monographs and keys. But if Jonathan Collwell IDs a Monkey Beetle or John Manning an Irid, I agree automatically because they are the world experts in those groups. If they are wrong, who on earth would know?
I agree that treating agreements differently from identifications is a cool ID. But then we need some additionally functionality. On iSpot that did agreements differently, one could not post an ID that was already on the observation: you had to agree to it. On iNat you can agree to a specific ID, to a community ID, or post an independent copy of an already existing ID (indeed, you can post a second copy of an ID that you made previously, which is weird, but handy if someone disagrees with you and you want to make a point - although I dont think that this was the intention).
Another difference from iSpot is that IDs and Agreements could not be altered. Once made, the only way to change them was to post a revised ID. That prevents people deleting mistakes (and any agreements made to it), and altering subsequent embarrassing explanations - which iNat allows. Users who deleted their accounts had their IDs reassigned as posted by Anonxyz (where xyz was a link to the user known only to site managers), and their reputation deprecated to novice.
I am not saying that iSpot was a good system, but include it here just for comparison and to explore options.