Heh, rene makes a business out of being different, and has some good ideas, but they do push it to far sometimes.
Sure I get it, a stoppie shows that the brakes are not a bottleneck, it's the traction. So sure, sometimes, on some bikes, with some riders, under some conditions you get perfect braking.
However in the real world there's various rim surfaces (aluminum, steel, carbon fiber), with a variation of water, grit, sand, snow, ice to complicate things. Cable have friction and slack. Rims sometimes are not perfectly round/true in both horizontal and vertical directions. Brake pads are rarely perfectly aligned (the alignment changes as the pads wear), rarely nice soft rubber (they glaze over with heat and/or age), and are rarely braking on perfectly clean rims.
So yes, I've done a stoppie with rim brakes, but the average performance of average hydraulic disc brakes greatly exceeds the average performance of rim brakes. Their other complaint about being grabby is highly brand specific, plenty offer great modulation. Not only to discs brake better, modulate better, and tolerate temp changes better better, but they also tend to apply more even pressure. Even small differences in trueness tend to create spots on the wheel that brake less or brake more.
I didn't realize how big the difference was, or the habits I had with rim brakes. Took me awhile to unlearn dragging my brakes when ever I hit a puddle, waiting for them to catch again.
Sure if you have a pro mechanic realign your pads before every ride you'll rarely run into an issue that rim brakes handle well. However if you spend more time riding than maintenance discs will serve you well.
There's a reason even the road racers, the most conservative of the bicyclist, are switching to discs.