I agree, it is simply a “this could benefit from having more people look at it”. It might be more people that think like me, or it might be others that don’t. I will usually only do so if I feel that “extra eyes” might help, which implies a certain level of knowledge of the taxa myself, and therefore I will typically do so with the expectation that the extra eyes will see the same as me! If I see an identifier that is making IDs I feel might be “over-zealous” then I will mark it as well.
I must say though, that I would tag in other iNatters that I have had dialogue with in the past, far more often than I would set the “can be improved” flag. The opportunity to hold or be part of further discussions represents too great a learning opportunity to pass up!