Imagine you're maintaining some program that intensively uses OpenSSL. It's 2014-ish, and some LibreSSL people come to you and tell you that you're using deprecated API and you need to upgrade for compatibility with LibreSSL. Sure, it's an improvement and maintains compatibility with OpenSSL, so why not.
Then OpenSSL 1.1 comes with some more API changes. You end up adding #if conditions to support both OpenSSL versions. And the next thing you realize, you've just broken LibreSSL because it pretends to be OpenSSL 2.0.0.
And when you patch it, you realize you're adding another ticking time bomb because LibreSSL will probably support the new API at some point too and you will have to add yet another version check to the code.
I am not surprised that somewhere in middle of that process upstreams stop taking LibreSSL seriously.