> we shouldn't design systems with dark patterns that take advantage of human frailty

First of all: «humans are frail», so the paramount social and individual objective, goal, is to overcome frailty (in cognitive and psychological and judgement functions).

Secondly: you are using a bad argument putting even innocent and somehow proper implementations in the set of "exploitative dark patterns".

And importantly: we the adults must not be bound in the Procuste's bed of a world for the use of children. If people cry when e.g. somebody multiplies 123 and 321, they must be brought back to health, and we must be in the condition of making our free and legitimate multiplications.