I think that the thing that is often missed in the discussions (but not by 1ab) re: discs is modulation. I’m not aware of anyone in the industry touting increased power- it’s discs’ modulation and consistency that are the key draws, driven in part to the often terrifying braking performance of carbon fiber rims in the wet. As cable routing has become more convoluted (for aesthetic and aerodynamic reasons), cable drag becomes more and more of a factor- and it’s something that sneaks up on you.
While I’ve never had trouble with decent quality rim brakes pulled by fresh, good-quality cables/housing against aluminum rims in reasonable conditions, start to mess with any one of those conditions and things can degrade slowly (cable & housing contamination) or less so (carbon in the rain). Faster? Maybe. More confident? Absolutely. And the thinking among many in the industry is that the wider tires they allow (~30c for a road bike) can be faster than the high-pressure 23s we’ve all been riding for ages.
I’m no fanboy -given the choice between wide tubeless tires at low pressures with rim brakes or 23c tires at 120psi and disc brakes I’d choose the former every time- but having ridden with discs for nearly fifteen years off road and on the road for about one, I appreciate the consistency and control that they provide. While they’re no reason to pasture a favorite bike, I see little reason to buy a new road bike without discs.