That's an interesting point, but because browsers decided not to use HTTP/1.1 pipelining and encrypted SNI is still only an optional thing in TLS 1.3, the clean

That's an interesting point, but because browsers decided not to use HTTP/1.1 pipelining and encrypted SNI is still only an optional thing in TLS 1.3, the clean signal you get from the separate connections, each of which is tied to a hostname, makes these attacks extremely cheap and "practical" in a way that isn't quite as true when you are dealing with commingled data from all of the user's simultaneous connections, many of which might be to the same host; like, seeing "the user requested 32 map tiles with these individual sizes" is very different from "the user requested a bunch of map tiles--maybe 32ish--and they total in size to this amount... that or they are watching a YouTube video". This article might be a lot more valid once the web has upgraded to HTTP/2, particularly if it manages to adopt encrypted SNI.