The point is that treating staff with disrespect is certainly not justified, but neither is it out of the blue, more often than not it is reciprocal behavior. Flyers are treated like rubbish by airline staff.
I’m not a professional flyer by any means - but I have flown many, many miles both domestic in the States and internationally. I can’t say that you didn’t experience that behavior from a flight attendant - I could absolutely see a flight attendant losing their cool with an uncooperative customer like that - but after having flown thousands of hours both domestic and international I can genuinely say that the situation you describe has never happened to me on either the flyer or employee side - so I’m led to conclude that it must be pretty rare.
Also, the fact that some people treat waitresses and service workers as punching bags that are "beneath them" socially, is a separate but related problem here.
I’ve never really experienced anything like it.
The casual disregard some US visitors have for staff anywhere is appalling.
In your example, it would be like causing a ruckus in a store, and being banned from all stores.
That's a much more serious penalty given how our society is organized, and seems like it should have some sort of judicial constraint.
The point of using the government no fly list is to pass the controversy onto something else.