9 levels?

I certainly wouldn't use NetworkManager on a server, but I was suggesting that people might use firewalld on their servers, not NetworkManager. Once someone has set up NetworkManager and firewalld on a bunch of user laptops, and they're going to set up a server, it makes sense to ditch NetworkManager (because they don't want its functionality), but it doesn't make sense to switch to some other firewall system they are less familiar with. Unless, of course, firewalld doesn't have a suitable trust profile to set statically for the server.