[thaumasiotes]

> Needless to say, the most prominent and memorable identifier being non-unique has all sorts of uses for trolls and spambots too.

Sure, but it has more uses for people who would like to have a reasonable name. This is just the "knives can be used to kill people" argument.

[notahacker]

The option for a reasonable name still exists (and site owners don't have to arbitrarily confiscate it to give it to more PR-worthy people), it just might be a slightly longer reasonable name with a disambiguator built into it instead of a common first name or cool dictionary word, and you get a reasonable URL as a bonus. I'd probably rather be found at instagram.com/johnsmithspringfield than instagram.com/jh9fjhfgjhg (or 'search for "John Smith" and scroll through 300 entries') anyway.

Of course with unique identifiers you probably don't get to call yourself elonmusk, POTUS or amazon