Distributions I prefer have never used NetworkManager and haven't changed network configuration in a long time. RHEL and its rebuilds have used NM for what feels like an eternity. Ubuntu is the odd one out here with its constant churn, afaik.
Same with firewall wrappers like ufw and firewalld. Either your distribution uses one and you just use whatever has been chosen for you, or it doesn't and you go with nftables (or iptables-nft if you prefer).
This is all only really a problem if your organization uses a bunch of distributions instead of standardizing on one, but then you probably have a lot more other serious problems than learning how to configure your firewall...
As a counterpoint, I evaluated FreeBSD for a project about a year ago and was really put off by its primitive service management (compared to systemd which I know pretty well and use its features extensively, they really do help in your daily work), and the three firewalls which all seem to be approximately equally supported and you never really know where to put your time. (Unfortunately, I had to pass the OS for other reasons which have no relation to its technical merit.)
I really don't get these criticisms, you have choice, having choices doesn't make a system bad, makes you have to make your choices, which can also be going towards systems where stuff is standard
Software is utilitarian in nature, the goal is the task, but, how do you accomplish a task with an infinite amount of tools? and not only that, but how can you be sure that the tool is secure and stable?
Networkmanager seems to be what things are standardizing on these days. Which, while for some reason I've always avoided networkmanager and used various combinations as alternatives, I'm all for having one most common standard networking utility for Linux.
I usually settle on networkmanager, since there's not a great alternative for dealing with wifi. However, it often delegates to a giant broken pile of fail.
Things can be much simpler on machines that connect via ethernet (including VMs).