I laughed out loud, there is no in-place upgrade mechanism for that in those distros and never has been, that is the nature of those distros. They release patch/security updates until they go EOL, which is measured in units closer to decades than years.
I don’t have a problem with BSDs. That’s cool you like upgrading in place.
The best and most laugh-inducing part of your whole point is that centos now not only allows you to do in-place upgrades, that’s the whole fucking point.