This is especially annoying on desktop Ubuntu boxes with automatic updates turned on. You're working on some frontend code and bam! nginx is down, the database is down.
It should only take a second to restart foo.service after updating foo. Why shut it down so early and wait while APT is updating the kernel and a whole bunch of other packages? Probably because shutting eveyrthing down makes it easier for the postinstall script to do a clean job.
YUM/DNF don't do this. They just update things and let me restart things at my leisure.