I hated when textbooks/papers did this. Half the time you can't tell if they meant to use the bold letter or if the printer was just being generous on that character. Made legibility quite a bit more difficult. BB letters are unambiguous.
Not the OP, but here's my observation: When I have to stop at a light until it turns green, I have to navigate the intersection while the cars around me are entering it as well. Suddenly there's a car trying to pass me, a car in the oncoming lane turning left, etc. If I can skirt through the intersection while the light is red and there's no transverse traffic, I can get through without interacting with any other moving vehicles.
I've also been involved in car(-car, not car-bike) accidents before where some idiot at a light was looking at their phone while stopped, and did something stupid when they noticed others moving in their peripheral vision. Plausibly, such idiots could be the cause of a lot of accidents at intersections.
For a good while, Yik Yak was very popular on my campus. Then when handles became mandatory, basically everyone stopped using it. Even after they back-pedaled, though, our feed was merged with several in the surrounding area, so we lost the sense of community we had with it on campus, and it never took off again.
I don't know about overall, but in my social microcosm yik yak was never able to recover its lost users.