I have always been very careful about what I put in writing in any form, including in the far off days of paper or pen. Letters go astray, people read over other people's shoulders, others quite brazenly pick up other people's letters etc and read them.
At least on forums we are hidden behind pseudonyms. Apart from a few people I have met at meet-ups - and that is consciously my choice, know who I am - and similarly, apart from the people I have met at meet-ups, I do not have the smallest clue who any of you are. I see your forum names, your posts may tell me where you live, in regional or county terms, and some details of your family, but beyond that we may have sat next to each other on trains, in the theatre, or spoken at meetings without having any idea that the person next to us is on GN and I would immediately recognise their peudonym.
You are, in fact, far more safely anonymous online on a forum with a pseudynym than in a letter to a newspaper with your name on.