Well SOME stuff isn't outing ... EG, when a husband has a hobby that is 'outing,' it's always bloody cycling or running or golf, which millions of men do! But some stuff could be 'outing...'
Personally, one reason I think people name change, is because if they start a thread and they get jumped on, and some people are quite nasty to them, (which happens very often on here,) at least they can just hide the thread and not post again under that additional name and go back to the normal one.
And they announce they have name changed, because if they don't, people say 'hmmm interesting first post.....'
and they get called a troll. Also, if someone has said they are 35, and they have 2 kids under 10, a boy and a girl, and they are a hairdresser, then that job (hairdresser,) along with the other details, MAY identify them to someone in real life.
If in real life, I am say, 52, and have 2 kids in their teens, and am a GP receptionist, I will say (under a NC) I am 49, I have 1 or 3 kids, and I work in a bank, because someone reading my thread may, just MAY recognise me from my description. Millions of people read mumsnet, AIBU is the most read, and 'posted on' board, and I know people who read mumsnet: family and friends, so yeah I will change details if I am posting something personal..
I will also NC... There's no way in hell that I would start a thread about something personal going on in my life under my name PurpleButterflyWings.