so i started with a joke, but um.. yea controlling account creation.. as long as its code base not centralised based. which is a tougher one to get around because anyone can change the source to crack the code locally..
Jokes are fine (but yes this is serious) - some basic rules in order to "create new accounts" would be that it would be "expensive to do so" (thus making it more "profitable at least in the short term" to just keep using the same account rather than *split it into two*).
The very initial accounts would actually come from "working on the project itself" which could be via looking at github commits or other similar things (so the decentralisation grows from a project that is not initially decentralised).
Where I am aiming this idea is a very different audience from the current "crypto-currency speculators" - I am thinking of of "blockchain apps" for things like franchise businesses (I also think it could be a great basis for a new kind of "social networking").
