It just takes unnecessary effort to keep up with what just works for Linux and I didn't see much benefit sticking to FreeBSD.
What I like with FreeBSD is the slower pace of evolution, so there is less breaking change per unit of time, that makes me spend less time fixing things while being up to date, and when it break there is always a good documentation available. Things I like in FreebSD: pf, zfs, bhyve, rc.d, good separation between user configuration changes and system configuration.
ifconfig still configures network interfaces (including wireless)
the init system is still the same
you still have the same three firewalls to choose from
the audio system is still the same
The internals are quite a bit different (and more capable), and I don't think zfs was in FreeBSD back then, but UFS2 still works.
If you want to experience twenty year old FreeBSD, to compare with modern FreeBSD, Apple has lovingly preserved it as the userland unix interface in MacOs, they've even got a circa 2000 tcp stack.
1. Ubuntu LTS releases are supported for five years -- Centos is for ten years.
2. FreeBSD updates are typically easy to perform, and the new system is not that different from the previous one. Things are where they used to be and you configure it the same way as you have for years. With Centos, there was a migration from yum -> dnf. With both Ubuntu and Centos the init system has changed from sysv -> upstart -> systemd. The default network configuration on Ubuntu has been replaced with netplan.
I guess what I'm getting at is that there is significantly more churn in Linux distributions and vastly less churn in FreeBSD. This could also be seen as a lack of progress, but I don't think that OP sees it that way.