I do think there's a difference between updating friends, family and workmates with texts and messages about your child's ill-health, to starting a thread on Mumsnet, and subsequently updating that thread numerous times, with intricate medical detail.
I don't think I would have the concentration or the commitment to do it.
On the other hand, I can imagine someone who is lonely and bored, starting a thread, and thoroughly enjoying all the attention and positive affirmations they get. Apart from Poorly Pam (and I do think that was true, with hindsight), most of the three part saga threads have been proved to be untrue. Especially when there is a cast of supporting characters like Lovely DH, Best Friend, Dishy Doctor and Nasty Nurse.