This is another example of MacOS being turned into iOS, which while there are some good parts, has on the whole, been very negative. The local network access restriction has been around in iOS for a number of years. It doesn't come up as often on a phone as most(not all, but most) Apps will use an Apple API to do local network things(Airplay, etc), and Apple system binaries have implicit permission.
The most egregious part, IMO, is that there is no way to disable it. My Mac is not a freaking phone. I don't use it like a phone. I don't want the low level system pieces(network, system certs, etc) to act like a phone.