Focused work should be challenging or at least require a person’s dedicated attention, which is not possible when distractions are a normal occurrence in a workplace regardless of whether someone has a mental or physical condition that makes them less functional in a “normally” loud workplace.
But for my friends with severe misophonia (self-diagnosed, for the most part), hearing chips crunch or lips smacking will drive them out of the room in abject fury. It is, according to them at least, uncontrollable and unavoidable and it turns what would be "mild annoyance" for most of us into "severe anguish". At that point it's not even about losing some productivity, but being driven into such severe discomfort that you can't physically be in the proximity of the sounds anymore and you start to hate the other person who's caused it, and it all just unravels from there.
There's a huge difference between that and "oh, well, that construction noise outside is kinda annoying, I hope it stops soon".
The open-layout office is hell for people who need quiet for focused work :( Sorry you had to deal with that.