"As mentioned earlier in this topic, the final RFC was not ratified until 2017"
This may not mean what you think.
RFCs don't usually get designated as "Internet Standards" until all of the following occur:
1. There is widespread support with multiple mature implementations.
2. The technology they describe has significant real world use.
... and importantly for this discussion:
3. The next superseding RFC for the standard in question is published.
Whilst sometimes an RFC gets reclassified as an IS retrospectively after it is published, that rarely happens, and it's usually only the next natural revision of the RFC gets published that the reclassification to "Internet Standard" happens.
e.g. NTP (the Network Time Protocol) is not yet an "Internet Standard", even though it certainly passes the first two tests (it's probably used by over 95% of devices on the Internet). If and when the current NTP standard RFC 1305 (published in 1992) gets obsoleted by a replacement RFC, then that RFC will become an Internet Standard.
The first "Internet Standard" version of IPv6 is RFC 8200 (published in 2017).
RFC 8200 obsoleted the previous IPv6 "Draft Standard" RFC 2460 (published in 1998).
A Draft Standard is normally considered to be a final specification,
and changes are likely to be made only to solve specific problems
encountered. In most circumstances, it is reasonable for vendors to
deploy implementations of Draft Standards into a disruption sensitive
environment.
so draft standards (as IPv6 was by 1998) are already considered mature, ready for production use and have multiple implementations, and a good level of both support and adoption.
Plusnet and the majority of the web runs on a "draft standard" version of HTTP:
HTTP/3 (HTTP v3) carries about 20% of all web traffic, yet is only a "Proposed Standard" (one rung below draft).
HTTP/2 is only a Draft Standard, despite carrying about 50% of Internet traffic (including community.plus.net).
HTTP/1.1 only became an "Internet Standard" in 2022, it's share of traffic has now diminished to ~ 30%.
I don't think Plusnet or anyone else is being reckless or premature by using the HTTP/2 "draft standard" before its eventual "Internet Standard" status gets bestowed - it's a far better choice than HTTP/1.1 for most purposes and has been for quite some time.
