> I assumed it's going to get adopted in no time due to how much of a ux improvement it would have been back in the day.
You might also be interested in SCTP[1] from the year 2000, which also hasn't gotten any traction so far.
[1]: https://en.wikipedia.org/wiki/Stream_Control_Transmission_Pr...
Probably partly because middleware boxes (e.g., firewalls) either didn't/don't support it and/or rules were written to only support "TCP" (as opposed to 'stream') or "UDP" (as opposed to 'dgram'; see also "DCCP").
Now we have HTTP3 which runs over UDP - where there is a will, there is a way.
Perhaps SCTP was ahead of its time.
SCTP over UDP came out in 2013:
* https://datatracker.ietf.org/doc/html/rfc6951
SCTP came out in 2000:
* https://datatracker.ietf.org/doc/html/rfc2960
Over a decade is quite a while in Internet-time.
Most firewalls are default deny out of the box and you have to allow things through. How many folks bother opening up SCTP/DCCP/etc?
Given that TCP also has at least one unfixable flaw, the only recommendation I can make is to use something UDP-based - which, to make sure you don't stomp on everybody else's traffic, means use the only popular one: QUIC (the layer beneath HTTP/3).
(SCTP over DTLS, that is...)