@Felthry Twitter users started using it because it made tags searchable with the built-in search engine
@noiob why specifically # anyway, and again, why are we not separating data and metadata
@Felthry probably because it's next to the @ on a US keyboard and not used for anything else
because it's a feature pioneered by users, who can only define data
plus remember that Twitter used to be a SMS service, that's influenced a lot of how it works