Using words that may be out of date or offence

When I see posts like this. I often wonder a few questions. (1) who was it who decided such words were offensive and when and what qualifications do they have to conclude it (do they have a phd in word use?). (2) Who is it who is offended and can people be offended on behalf of others? (3) Can someone speak and presume on behalf of others even if they are part of the group affected and even if they are not part of the effected group? Personally I will use the words I wish to, and if people are offended because I may use words that they deem out of date or offence then tough.