[kixelated]

Are you referencing this line? > 2x the packets, because libsctp immediately ACKs every “datagram”.

The section is about data channels, which uses SCTP and is ACK-based. Yes, you can use RTP with NACK and/or FEC with the media stack, but not with the data stack.

[the8472]

TCP can coalesce acks for multiple packets, can't SCTP do the same?

[kixelated]

The protocol can do it, but libsctp (used by browsers) was not coalescing ACKs. I'm not sure if it has been fixed yet.

[Sean-Der]

SCTP can (and does) a SACK[0] isn't needed for each DATA chunk.

[0] https://datatracker.ietf.org/doc/html/rfc4960#section-3.3.4