Instagram/Twitter/Github: Informal market which favors the needy, and somewhat the connected.

Phone service: random UID as you suggest, users put aliases in address book. Works great. Plays no favorites, unless you want 555-555-5555.

Internet DNS: restrictions on valid names (to certain TLDs) which are gradually lifted as our name needs increase. Expiration, which favors the needy. Cash market, which favors the rich and needy.

Email: Similar to DNS, but mandatory attachment to domains broadens set of available names. No expiration policy at high demand domains (i.e. gmail).

Follow me on Instagram: @f9ab8ed9dacd8724bc

Actually (edited), if you use @whatever in your comment, it should resolve appropriately for me. Just put a name:link pair to whatever account in your about text.

here's a link to my instagram: http://instagram.com/f9ab8ed9dacd8724bc/#

That's fine for email, but services like Instagram thrive on literal word of mouth with people saying it over the phone or over TV or radio. Watch some TV and see how many adverts include the Facebook logo or a hashtag (implying Twitter, although a competitor could steal that market overnight). It's not just about clickability, it's also about having an identity easy enough for people to remember to check out. 'I haven't looked at Joe_Blow's Instagram in a while' is an easy thought to form, having to perform a search to find the random string of the actual account name, which is unrecognizable for most people if the search returns more than one result - that's a pain.

There's nothing wrong with vanity tags. Similar to 'verified' accounts.

And if you're referencing me from your phone, you could alias me as @knowsnothing and change my icon to a koala if you wanted to. That offends me less than me having to come up with @awesome_sauce314 to use some photo sharing service, which I'd need to share among friends, coworkers, family, strangers, etc.

I don't disagree, I just think that most service providers find the 'first come first served' model easier to implement. Having said that I'm struck by how this seems to matter less and less on Twitter, eg many celebrities have somewhat random-seeming handles.

Agreed on both points. Maybe starting with ICQ back in the 90's has overly biased me; things certainly seem to work well enough as they are.

Underneath all this is the problem of identity generally.

How will someone born today have any hope of any kind of usable identity in a system that allows only one instance of a name.

Says the guy with a three letter handle...

We should just name out children random hash strings.