Braking bumps (in my mind) are the product of folks braking hard into a section of trail (be it a berm or whatever) and the resulting "corrugation" of the trail surface due to erosion. They aren't a designed thing. I think the folks talking about the diddy triple or whatever it is are discussing a "bad" feature, not braking bumps.
BB's are the result of a number of factors either occuring individually or more often, IMO, as a combination. Some of these factors are within the control of various parties; trail designers, builders and riders.
E.g.
Even with the most perfect trail, someone going to fast and braking hard (subjective) into a feature, typically a berm or corner will start / exacerbate / make massive BB's.
or
A trail which flips "character" between sections that encourage speed and then tight, slow speed features / turns is likley to exacerbate the forming of BBs.
or
If a trail builders doesn't armour (say rock slabs or really well compacted surfacing) on the approach into a feature where riders are likley to be braking hard then this makes it more vulnerable to BB formation.
To lay it all at a designers door is unfair and incorrect.
Also, living in the real world of trail design and building, life is full of compromises be they restrictions on space, materials, cash, rioder skills etc.
AHwiles seems to assume as well that given perfect trail design this would solve all BB issues. IMO this would only occur if you also had perfect (not necesssarily highly skilled, just perfectly competent) riders.
And back in the real world …… 😉
Tim, building fast / slow, tight / open, good / bad trails in Yorkshire with SingletrAction for a few years 😎