You are right, Nelliemoser most posters wait until they feel they have their "feet under the table" before giving us a lot of information about themselves. Most only post quite short messages for the first wee while, too, not a whole page of meandering guff that tells us everything but the kitchen sink. You would need a psychiatrist's couch and a thick notebook for Trevor's stories (Trevor the self-styled shy, nervous introvert with no self-esteem).
The other point is that in giving support to posters who tell a sad story, it is tempting to post personal details about how "exactly the same thing happened to me" or to describe in detail your own absolutely awful experiences with relations. It is done with the best intentions, to put the poster at ease and make them feel they are not alone, but remember it is possible to be helpful without exposing your own private life.
You make yourself vulnerable by putting stuff into the public domain. Anyone at all can read the posts on these forums, without joining Gransnet, and there are some sick souls out there who search for such things. Your family and neighbours could be reading your story, and recognise you or the people you mention. Be more general in your replies.