You make valid points.

I have some, too. We all type things we later think better of - the internet does have a considerable ability to forget stuff as the search engines deem it less current or relevant - and context is everything.

An off-colour remark in a thread of bad-taste comments might well be picked up and criticised at the time but the real danger seen here is of cut-and-paste recontextualisation; remarks that in context can be either discarded as bad judgement or even the fiction of an unwise mind may gain a new life as an accepted truth when constantly repeated; this also defeats the tendency of search engines to forget, or bury them in a sea of inane drivel

If a person took to following you around town loudly repeating things you'd said, out of context and in the most defamatory way imaginable you'd either sue them or get an injunction; on this site such actions are harder to bring and other tools you propose such as an ability to close your own ears to them while everyone else witnesses the full detail, and thus lose your right of reply... are of little use.
(Carpe Cyprinidae, Sat 28 Dec 2013, 1:16, Reply)