Theoretically, you have a point. Practically, you are reading this comment on a website that not only does exactly this, but refreshes the entire page (rather than a small block of HTML, intercooler-style). The performance benefits are evident.
Every time you collapse a thread, that's saved on the server. Then, if you return to the page, it will render those threads collapsed. So that's a decent amount of state.
I disagree. It’s Boolean and flat (there is neither sequential nor nested logic around the state). It does recurse for each sub thread, but only in the case where there is no state. There’s also no business logic built around it, only display logic. It also is updated from exactly one location in the application.
That said, it’s a very simple and effective design. It’s an excellent program. But it’s not a fair comparison against other applications which, for one reason or another, need significantly more advanced state.
I mean, this website only loads a very small amount of text and has barely any user state besides a list of comments and posts. I would hope that it loads quickly.
