First, what I said was in half jest. Though if someone really did do that to a distracted walker, I would record it on video, put it on youtube to shame the distracted walker, and laugh loudly.
Second, think about "glancing down at their phone for a few seconds." I live in a fairly crowded city, with an old subway system. This means narrow sidewalks, narrow stairs, narrow tunnels, narrow platforms, and lots of people. Count out 3 seconds, using Mississippis or whatever method they used in grade school gym class. That is a long time to not be looking at where you are going. In that time, you could probably pass 3-6 people walking the other direction. In that amount of time, you can walk 15 feet. We have had instances of people falling on the tracks because they were walking on a platform and glanced at their phone for a second too long; not only injuring themselves but causing delays for everyone else using that subway line at the time.
When two people approach each other on a narrow sidewalk, each moves a tad to the side and shifts their shoulders so they can easy pass easily. People looking down at their phones for even a few seconds don't do this. If a person is looking down and doesn't do this, and we end up bumping shoulders, if their phone happens to fall and break, so be it. I have also noticed people tend to slow down when they are looking at their phones - I don't think they even notice they are suddenly walking a lot slower. But everyone behind them notices. If someone should happen to bump them as they pass and the phone happens to fall and break, so be it.
If someone must glance at their phone for *one* second to check something really quick and glanceable - fine go ahead. But if someone wants to answer texts, comment on social media, reply to emails, update calendars or to-do lists, or play games on a street with other people on it, then stop walking and step aside. There are plenty of places to stand without being in the way. There are plenty of coffee shops at every block to take a quick break. Anything else is incredible inconsiderate of everyone else around you.
