I never saw the point of a non-smoking section. The tables immediately around you aren't, but the ones over there are you, often had to walk through them, and there still being a general cloud of smokiness in some of them.
I never considered it before, but yeah this did slowly happen over decades of time. When I was young it was just the norm and you saw it everywhere and didn't think of it or notice it, but last time I was in Oklahoma (a few years ago) it was disgusting stopping at a hotel and being asked "smoking or non?"
First time I heard "smoking or non-smoking" was when checking in at the airport. It was at some point in the 70s that it started in restaurants in California, although it didn't really become a thing in other states until a few years later. When I started working, smoking at the workplace was a common thing. I don't think most smokers intentionally meant to harm anyone (even if they knew they were harming themselves), or at least, they probably didn't think about it very much.
A lot of this also happened with gradual, steady increases in cigarette taxes, and that may have also contributed to smokers' complaints.