Thinking Too Hard and Running With Scissors

What is it about writing an online journal that's different than writing in a private journal? I've been trying to keep a physical journal, at the suggestion of my therapist. It helps, that's for sure, and I thoroughly enjoy the physical action of writing with a pen on paper - helped along by my general obsession with fountain pens and inks (allllll the pretties!). But the pull to write in a public forum behind a veil of anonymity - why? I'm not just asking this of myself, either - why do so many others do it as well, some obsessively?

I think it's because when you put your thoughts or writing out online, you know they can be heard. They might not be, but they could be, if someone stumbles across your blog. Somewhat like talking to a therapist, it's a release, like popping a balloon with a pin. I am NOT suggesting you substitute an online blog for a good therapist, by the way. But it does feel good, to have a place to braindump without judgment. Oh, I'm not kidding myself - the internet is full of judgment, haters, and bullies - but there are also plenty of good people, and I'm not worried about an anonymous troll. On the internet, I pretty much ignore anything that smacks of hate or negativity - I don't have space or time for that in my life.