I’m guessing it’s moreso that Gnome likes to make changes that can break things like extensions, and they probably don’t hot swap shell components. The biggest reason you need to restart after Linux updates is that certain things are only loaded during the boot process (i.e. the kernel, initramfs, some boot or filesystem options) and can’t easily be reloaded while the system is running. But you update something like dnsmasq, you probably just need to restart the service. At worst you need to reload the systemd daemon for config changes to take. And if you’re just updating binaries, unless it’s something like PAM that can also be not fun to restart and is constantly running, you probably don’t need to do very much.