That last paragraph is what I was thinking. If the labels exist in many places, then anyone can utilize or present them (or not) however they want... there must be a better way to create them, though. 90% of this conversation is well beyond me, but lacking an efficient way to do it, is the only thing that holds me back from labeling things now.
Discussion
I’d love to see one or more nostr clients implement tags. Probably worth looking at how Pubky does it from a UX perspective.
I hate to use Amethyst as an example of everything but there's a 'timestamp it' option in the 3 dot menu on each note. A 'label it' option would fit really nicely below that. The same could apply to any client that offers note menu options beyond like, reply, and zap, such as raw event data & n-prefixed idenifiers (or whatever those are called). It would be tucked away but easily accessible to anyone who want to use it. I don't think it would complicate the UX any more than that stuff already does. Talking a client developer into adding it, I think, would be the hard part.