I'm detecting a bit of a goady note here... no? I don't know I'm just sensing a desire to find the weak spot of this theory and see it come crashing down.
Anyway will answer in good faith. I don't think there is really a weak spot, it's not some "out there" suggestion when you boil it down to what it really means. And obv just like every parenting goal (minimal screen time, always saying please/thank you, never shouting, eating healthy balanced diet etc) there is the idea and then there is the reality.
The way I understood this method when DS was little was that no should only be the answer to a direct question/request, not that it's a dirty word and should be avoided at all times. It's the command of "no" that is the problem, if that makes sense.
It's just two things about "no" that can be improved - it's vague, same as "stop that" "don't do that" etc. Very little children and some older developmentally delayed children don't have the framework that adults have to instinctively understand which of the actions they're currently doing is the wrong one. It's better to identify the action directly either by physically stopping them from doing it or verbally communicating what is wrong. I used to use words like "hot" and "yuck" or "not yours" when DS was a baby rather than no because these are more communicative/specific.
Then the second issue is it's negative. Not in the way of "My precious baby must never hear an angry word" because of course, life doesn't work like that, there IS negativity just the same as positivity and you need a balance. It's more that it's grammatically negative, as in it accompanies a sentence which includes "not". No shouting, no running, don't throw food, stop hitting etc all tell the child what you want them not to do. It's the old "don't think about an elephant". It's more productive, more direct, faster and less likely to invoke argument to rephrase and say what you do want. (Talk nicely/we walk by roads/put it on the side of your plate/be careful (or) gentle) It does take a bit of practice at first but you very quickly get into the habit of it.
DS always responded just fine when other adults told him no. It wasn't that he didn't expect to ever hear the word, it's just I thought that other ways of communicating "that isn't okay" made more sense.