I've muted a few people for spam such as constant excessive newslinks, or interminable t-shirt postings. I muted someone promoting Satanism, but that is just my personal preference. And yesterday I was disgusted by a full-on hard porn gif posted as a comment on a trending article. Like @steevc I've only muted a handful of people, but I'm very grateful for the option. I don't need my day soured by offensive or annoying posts.