I remember people were abandoning localstorage a while ago because of some fundamental problem I can't quite remember right now. Not sure if it was difficulty in keeping in sync which the author mentions or the fact that it can't be scoped in a way to share among subdomains. I'm sure someone here will have a better memory than me.

Edit: after some basic research among other complaints are: bad performance, synchronous, bad security model, only strings, limited to 5mb, no access to web workers.

Localstorage has its uses but shouldn't be abused to store everything in it.