Permanent accounts exist but they are admin/moderator/janitor accounts (board mods/janitors included).
The most consistent way to maintain a verifiable identity is tripcodes. In the name section you put username#password and the server generates a hash for that user which can be used and verified in all threads and boards.
This post is an example of a tripcode, if you look at the name section
Also no profile pictures. Should've mentioned that, but images with posts are fine