Sometimes rants like this are biting indictments of the state of things, but sometimes they're just a bit of laziness.

The web is a constantly evolving platform. There used to be many things that were impossible to achieve on the web; that number is less now than it used to be thanks to the addition of new APIs (LocalStorage among them), but it's not yet zero. In particular, we don't yet have an API to achieve what jwz wants to do. LocalStorage was clearly not designed with this use case in mind; acting surprised when your awful hack turns out to be unreliable seems a bit disingenuous.