I tend to only agree with genus if it’s a hard-to-ID to species-level observation so that observer gets some indication they are right, rather than left wondering if it’s even remotely right.
A good example are prickly-pear cacti: Opuntia. There are some that can be IDed easily to species, but most just stay stuck at genus. Some discussion in: Good Field Guides for Opuntia
Otherwise, I think some folks agree to just genus for practice/fun? One downside with this, at least on the android app, is that if something is IDed to species and an identifier suggests the genus, it doesn’t show whether it’s disagreement with species or certainty about genus.