Where I live, the primary goal of blocking vehicle traffic from cutting through is to protect "neighborhood greenways" from getting inundated with car traffic. These are specially designated bike routes on neighborhood streets that are some of the best, low stress, popular pieces of bike infrastructure I've ever used.

So here, at least, these efforts are a terrible way to keep riff raff out, as they make your street far too attractive to riff raff using non-motorized transportation.