Here is another story on the incident and it allows comments too.

The comments here are much better, with only a few people blaming the cyclists.

I think the difference is the comment system. When Facebook handles the comments, most people ate not anonymous (unless they set up fake Facebook profiles, which I suspect Tammie did) and so they put more thought into their posts and think about how it reflects upon them.

I think this comic explains it well. (Warning: bad language.)

Here's another story on the incident. Comments are not on Facebook, and therefore bad.