This is still a thing. The problem is with any modern complex network eventually the routing happens through a system that is brought together somewhere in the middle. Just like cloud providers with all their redundancy can be brought down by a broken DNS configuration so can communications system at a point where they connect to the same network. The old analogue days made things easier with analogue multiplexors but these days a mismanaged routing configuration is a single point of failure, even if hardware isn't.
I do question why a faster rollback mechanism wasn't in play when the upgrade was botched.
But then I saw Motorola and don't question anything anymore. I've dealt with Motorola infrastructure before, in two countries (admittedly only for 5G and land-mobile radio systems), but they were very much a group which sent out people to work on critical infrastructure whose capabilities extended to following the written instructions in the manual and needing to call someone else for help when that didn't go exactly 100% according to plan.