Restaurants are so loud too, which makes it worse if you are hard of hearing. And some parents are self absorbed I completely agree. Some people get drunk and laugh & talk decibels above what is comfortable.
I think it is the behavior that is objectionable not the age. But I wouldn’t want to go anywhere we were unwelcome. Restaurants can chose dress code, age code etc. with no complaint from me. Just as I think bakers & caterers should be comfortable with the events they are working for/at not compelled. I had no trouble finding upscale places and if some few were unavailable for our family it was not a problem to me. I really can’t think of anywhere I wanted to go (after checking the menu) that we weren’t welcome.
You hit the nail on the head. Behavior! Have a plan. Toys, coloring, snacks, even!
For the record I would not go to or not go to a restaurant based on whether children are allowed in or not. But we probably would not return if we had a bad experience.