https://wiki.debian.org/DebianTesting#Best_practices_for_Tes...
A package manager should in my opinion leave daemon stopping/starting to the administrator, as they know their configuration better than any package manager ever can.
Also that behavior isn't unique to Debian at all.
These days we mostly deploy our stuff using containers anyway, and for my own personal machines I've just switched to Arch Linux since.
Stable is great for letting up a server and let it run on its own for years without any maintenance (HN warning: No maintenance is of course never a good idea, but at least Debian made it possible)
Testing ran in update conflicts at least once a month, but it was generally easy to resolve without bricking.
Unstable, well, the name says it all.