Because of broken interception proxies. In many cases, these prevented connections from being established at all if either side of the connection even just anno

Because of broken interception proxies. In many cases, these prevented connections from being established at all if either side of the connection even just announced 1.2 support. So it was disabled by default and in consequence it remained niche which didn’t exactly improve the situation with broken middle boxes. It also made implementing it in various SSL libraries somewhat low priority (see OpenSSL) Only as the security of pre 1.2 started really crumbling and once the Snowden revelations moved security to somewhat higher priority in the public perception, it started to at least become possible to enable 1.2 at least on servers. Frankly, I'm impressed we actually got to where we are at now. For a long time between 2008 and maybe 2015 it really looked like 1.2 was dead in the water. Now we're transitioning to 1.3 and history is repeating itself: despite going great lengths to hide the differentness of 1.3 to existing middleboxes, they are still breaking 1.3 connections causing more and more bad hacks to be added to the protocol. A protocol which supports version negotiation since the beginnings in the early 90ies btw.