Networking on linux is wildly powerful. Most desktop/SOHO installations would just be Wifi + DHCP. Maybe some VPN in the mix. But on the other side of the scale, there are routers with complex netfiltering, vlans, crazy GRE Tunnels, Tun/Tap, Wireguard, macvlans split between namespaces, bridges, etc, you name it.
Defining a straightforward configuration structure for that complexity is going to be insane. NetworkManager + Debian's /etc/network/interfaces (IMHO) seems to be a good fit: auto config w/ a GUI in NM in the simple case, and if the interface is listed in /etc/network/interfaces, you can do it anyway you want with Debian's system, with pre-up, up, post-up, post-down, etc scripts to your heart's content to setup whatever complexity you need.
My main gripe hasn't been that I want something done an exact way. It's that I want to achieve some semblance of what I'm trying to do in a reasonable amount of time.
NetworkManager is god awful in this regard. Even for simple desktop uses, if I want something more advanced than simply connecting to the Wi-Fi (even this requires finagling), then I'm fucked.
For example, I've been trying to find what it is that keeps overwriting /etc/resolv.conf.
After reading through various man pages and online forums, I still don't know. Instead, I just stick to one access point, and manually write to /etc/resolv.conf everytime I boot.
Compare this to OpenBSD: nothing fucking touches my /etc/resolv.conf. That file is mine. I write to it and other daemons read from it.
Defining a straightforward configuration structure for that complexity is going to be insane. NetworkManager + Debian's /etc/network/interfaces (IMHO) seems to be a good fit: auto config w/ a GUI in NM in the simple case, and if the interface is listed in /etc/network/interfaces, you can do it anyway you want with Debian's system, with pre-up, up, post-up, post-down, etc scripts to your heart's content to setup whatever complexity you need.