> For the risk of shock from an electrified appliance, that’s what the ground is for
Ground does not protect against every shock hazard! Devices can fail in many ways where live parts are exposed without contacting the grounded casing. Also, imagine a little child poking a metal stick into the outlet. Now you'd better hope that outlet has GFCI. Modern code does not call for it in a child's bedroom, does it?
Edit: To be fair, modern receptacles should be tamper-resistant, but then imagine a child reaching into a lightbulb socket, or cutting through a wire, or the insulation on a wire becoming damaged, etc. pp.
> for all practical purposes you almost do have [GFCI] on every circuit
But there are still gaps! I got shocked by an old clothes iron once (and I'm glad it tripped the RCD at the panel). Bedrooms and living rooms can have electrical faults too!
Another advantage of RCD at the panel is that it protects all downstream parts of the panel and all circuit wiring too! A lot of fatalities come from people working on live wiring. (In fact, many electrocution deaths are electrical contractors.) Now sure, they almost certainly weren't following correct safety procedures, but still, a lot of them could have been saved by an RCD. Some people probably die changing their light bulbs. That's preventable by installing an RCD at the panel, so that the entire circuit is protected, not just everything plugged into a GFCI outlet.
> To me seems like people are hating on a pretty great system. [...] localized fault detection [...] would seem like an advancement
I agree that localized fault detection, all else being equal, is an advancement. But if it comes at the cost of no GFCI protection at all on other circuits, I'm not sure it's worth the tradeoff.
Hundreds of people in the US die every year from low voltage electrical shocks. This number used to be a lot higher before GFCI was common, but it likely could be lower still if GFCI was required everywhere.
Obviously it would be best to have broad coverage and localized tripping, but if I had to pick one, I'd choose broad coverage. Calling it "going backwards" misses the concern of how much is protected, rather than just how localized the impact is when there is a fault.