Forcing bikes into conflict with cars is of course going to create problems. When I first started riding being on a sidewalk was fine. If that wasn’t available there was usually a sufficiently wide breakdown lane. Only fools and couriers rode in busy urban environments. But with the big push for bikes both municipally and on the basis of personal preference they had to get bikes out of conflict wirh pedestrians on sidewalks, but in built-up urban environments where there isn’t any room to put in proper bike lanes. It’s just a recipe for inflamed tempers. Even on roads that are more suburban, a couple of 18mph bikes blocking a 45 mph road is stupid even if they have a right to be there. But we need more bikes.
No, riding on the sidewalk was never "fine". I know it FEELS more safe, but cyclists are struck more often and killed more often per km of sidewalk than road. And I am never okay with pushing risk off on other people because I'm afraid to accept it myself; even if riding on the sidewalk were safer for me, it is less safe for everyone else, so I don't fucking do it.
Dude(ette), I’m over 50. It was “fine” in the sense that it was what we all did and there were rarely any rules against it. I don’t know where you’re getting that I said it was acceptable in the modern context, in fact I stated pretty much the opposite. You’re making controversy where there really isn’t any.