>the few distributions that did switch to libressl eventually switched back
Note that libressl supposedly improved openssl compatibility dramatically after that.
Also note it would have been a very different scenario if Debian or Fedora actually made the switch as they should have, rather than a few smaller distributions.
Instead, incompetence was rewarded, with plenty of money thrown openssl's way. This has, in hindsight, proven to not have been a good decision; code quality is still bad, and libressl is still a world better.
Debian has a humongous package library, the biggest of any distro if I'm not mistaken. They need full drop-in compatibility between libressl and openssl if they hope to replace the latter any time soon for all those packages.
The (current) compatibility is closer to drop-in than not. Most of these packages have maintainers and an upstream. It is just a matter of getting it done.
There exist distros using libressl and musl, proving feasibility.
Note that libressl supposedly improved openssl compatibility dramatically after that.
Also note it would have been a very different scenario if Debian or Fedora actually made the switch as they should have, rather than a few smaller distributions.
Instead, incompetence was rewarded, with plenty of money thrown openssl's way. This has, in hindsight, proven to not have been a good decision; code quality is still bad, and libressl is still a world better.