[skybrian]

Wikipedia does pretty well with redirects and disambiguation pages. Email can be forwarded. It's more difficult if you don't have a redirect mechanism.

I don't think any of us would prefer a meaningless number to a username? But you can create a new account if you wish.

And of course we use meaningful names in source code.

One scheme I like for URL's is a meaningless id followed by an SEO string in a URL, where only the number is used and it redirects if the SEO string doesn't match.