Once upon a time, Stephen John Smoogen smooge@gmail.com said:
The reason is that having 1 way to configure networks makes it so the developer and tech support only have to diagnose issues from 1 set of tools versus two different ones (and occasionally 2 competing ones if both are trying to do their job at the same time).
Not only that - the hodge-podge bash network scripts are kind of a mess. It is impressive that they do what they do so reliably after so long, but every new feature appears to have been hacked in by a different developer, leaving parts of them almost indecipherable.
That's not intended as a criticism of the scripts or the people who wrote that code - it's just that IMHO they managed to go beyond what is reasonable in bash scripting, which makes for a difficult to read (and I'm sure fix/extend) set of scripts.
And even on servers now, there are often dynamic network changes that work much better with NetworkManager than the old-style static scripts. Containers, VMs, and VPNs all come and go, and work better with a single system configuring their networks (rather than each layer implementing their own setup).