I think one other major reason SCTP never went anywhere because performant SCTP NAPT is impossible.

With UDP, TCP and SCTP, if you need to change ports in the header, then you need to update the checksum. The traditional TCP/UDP checksum is kinda crap, but this works in its favour here, because you can just perform a corresponding and easy adjustment of the header.

SCTP protects packets with a strong CRC32C checksum. This is on the whole a good thing, but you can't do the twiddle trick with CRC32C. If you're rewriting ports, you need to recalculate the checksum over the entire packet.

This means that linerate SCTP NAT accelerators have never existed. On the whole, what SCTP NATs exist only do address translation: If two people try to establish outbound SCTP connections from the same source port, the second person's connection just gets dropped by the NAT.