If for instance the OP referred to 'fat mums' in her thread title, everyone is understandably brilliant in pointing out that this isn't nice etc and you then change the title it just makes the thread look wrong.
Someone coming to the thread later will have no idea what everyone was on about.
I can understand editing for privacy (i.e. gave a location accidental) or if it's a sensitive subject, but because the OP was a bit of a knob?
Really?