Systemd is 13 years old.
As far as I'm concerned, the complains against churn run out after the project is old enough to drink. Especially if it's not just well adopted, but by far the most popular option.
In general, having open source but being afraid to change it sounds like hell to me. I personally believe in Linux & open source because it lets us keep improving & iterating & changing. Open source embodies the soft in software, and is the best vector computing society has for bringing light & clarity to a confusing but powerful man-made microverse.