I think this is a clear example of “I know what is best for you”. This kind of no-pagination is really nice if you are looking for some very specific context and easily breaks down when doing anything else.
Example: Sometimes I look for some tweet that I saw in my timeline a while ago. Can’t use search (that sucks btw) because I don’t know the specifics of the tweet but I know that I’ll recognize it when I see it. So I scroll, and scroll, and scroll… until I get bored with the extremely long page (if only i could skip the first hour and jump directly to the page 10?), or even worst, some problem happens and I have to start over again.
Also, like @Timothy Collins said, good look when trying to send the link to someone: it just doesn’t work.
Some comments say that if no-pagination doesn’t work is because everything else is badly implemented. Well, pagination might not be perfect but it damn sure helped to circumvent those problems way better than the infinite scrolling gimmick.