The problem with standardizing bad crypto options is that you are then exposed to all sorts of downgrade attack possibilities. There's a reason TLS1.3 removed all of the bad crypto algorithms that it had supported.

There were a number of things going on with TLS 1.3 and paring down the algorithm list.

First, we both wanted to get rid of static RSA and standardize on a DH-style exchange. This also allowed us to move the first encrypted message in 1-RTT mode to the first flight from the server. You'll note that while TLS 1.3 supports KEMs for PQ, they are run in the opposite direction from TLS 1.2, with the client supplying the public key and the server signing the transcript, just as with DH.

Second, TLS 1.3 made a number of changes to the negotiation which necessitated defining new code points, such as separating symmetric algorithm negotiation from asymmetric algorithm negotiation. When those new code points were defined, we just didn't register a lot of the older algorithms. In the specific case of symmetric algorithms, we also only. use AEAD-compatible encryption, which restricted the space further. Much of the motivation here was security, but it was also about implementation convenience because implementers didn't want to support a lot of algorithms for TLS 1.3.

It's worth noting that at roughly the same time, TLS relaxed the rules for registering new code points, so that you can register them without an RFC. This allows people to reserve code points for their own usage, but doesn't require the IETF to get involved and (hopefully) reduces pressure on other implementers to actually support those code points.

TLS 1.3 did do that, but it also fixed the ciphersuite negotiation mechanism (and got formally verified). So downgrade attacks are a moot point now.