I can easily identify an orange tree without memorizing Citrus × sinensis, a weeping willow without ever having heard of Salix babylonica, a palm tree without having an opinion on this menagerie of tags. Applications like iNaturalist are very useful but shouldn’t be a prerequisite for adding this sort of information to the map.
Editors already give mappers the opportunity to jot down the common name using keys like species:en. But data consumers require a more dependable scientific name. It’s that translation that typically requires an external resource, if not Wikidata then something more encumbered. If the editor could persuade the mapper to volunteer a little more detail, then I don’t see how this would be worse than telling mappers not to bother. If iD’s existing field for the species’ Wikidata ID would display descriptions like JOSM or images like Wikidata itself, then mappers and data consumers would be less likely to confuse plantain the weed with plantain the fruit tree.