STARTTLS command buffer smuggling was already a known issue long before 2014. In particular, the deluge of CVEs for MTAs started in early 2011, and it was obvious from the nature of the issue that it wasn't limited to SMTP, but rather pertained to lower level I/O interfaces common to network facing servers generally.
I worked on a project that filed bug reports about this 19 years ago. We blocked the clear text port, full stop. Can't count on users to config things correctly, even programmers.
I don't mean to be difficult, but in the spirit of being forthcoming:
"Called it!" posts really turn me off. You were right before, that's cool. What else can you add to a potentially interesting conversation? Bring your audience along for the ride..
I'm much more interested in any new insights you have on the matter!
Best wishes and take care <3, and again, I'm sorry, I wish I had the perfect words to connect with you.
Their blog post from 2014 does seem to "call it" quite succinctly, with a rather beige background.
This is a called it post with evidence. Why not read it! The current post has only just been ... posted. I'm sure Andrew will have an angle (if he can be arsed) but he does get to call it: "Called it".
Words are never perfect unless they are conjugating to a particular tense 8)
I'm very glad that Hanno et al gave this the thorough look that it needed and that the IETF no longer favors STARTTLS.