There is an older thread on this topic.
general consensus on etiquette regarding recruiting ids from specific identifiers
In my experience, the acceptance of @mentions is very dependent on the individuals involved. I know several researchers who use iNat regularly and are very active identifiers on the site. They generally don’t mind tags for unique or difficult-to-ID species in their fields. However, nobody has time time to be tagged on multiple common observations, which is where things break down. I am aware of one poster who will often tag 2 or 3 people for insect IDs within a day or so of posting. In my view, that shows a lack of patience and is an imposition.