I don't get it.
There's plenty to moan about with Mumsnet. It's not the most user-friendly when it comes to replying to people.
But one feature that is helpful is See All. It takes seconds, literally, to see whether the op has updated. Why wouldn't you use it if the thread you're posting on is already a few pages long?
Is it just that people don't give a shit about 'discussion', they just want to do the online version of standing up, yelling an opinion and walking away?
Apart from anything else, it makes people look stupid when they're imploring a poster to get over something they've already got over 3 or 4 pages ago...