[ithkuil]

The clients are free to make another "connection" and get a new session id every time they want. It's similar to http connection reuse: the src ip-port + dst-port also acts as a "session identifier", as long as multiple requests flow throug the same TCP connection.

[josefx]

Browsers are also free to use per site caches instead of a global one and sadly we ended up with just that because it turns out you cannot trust the internet with user privacy in any way.

[majewsky]

Bad example. Browsers have had per-site caches since between 2013 (Safari) and 2020 (Chrome, Firefox).

[ithkuil]

Yeah that's sad. My take was just that the problem is not caused by the transport protocol.