I'm not really seeing the argument. I've never had a derailleur break, if anything, this sounds like some supreme yak shaving. Granted, I don't ride bikes for a living, but I ride a bike every day and durability isn't even remotely as big of an issue as you make it out to be.
I have broken derailleurs, and I’ve also had them bumped out of adjustment and damaged at bike racks.
Switching is probably a bit of an unecessary faff. But if you want a drivetrain that can be ignored or neglected and never complain, an internal gear is really great.
For a commuter bike it also allows you to fully cover the chain and chainring if you want.
Once the bike is dropped drive-side and the derailleur hanger is bent, all it takes is a normal ride to catch the derailleur in the spokes and you get a very expensive repair.
