[aeturnum]

First: you are not alone, that's normal.

Second: I think they are leaning into the surprising and sometimes pleasing juxtaposition of conversations that can be happening "close" to each other. Like, I'll click into a tweet, and generally the first "thread" is the one where the OP replies to themselves - but that's not always the case! Sometimes another reply is more popular and they will swap it.

I think they are trying to give you a sense of how the conversation has gone - when they break the thread they are showing you that, based on activity, other people are ignoring the thread and paying attention to this other thread. It messes you up if all you want to do is see what the OP said, but if you are there to see "why people care about this tweet" (also common) it's important to understand where things fell apart.