Avoidence of responsibility
The founder of "mumsnet" is not an authority on anything other than how to create a social network that brings together *some* likeminded people.
She has no special authority on how to regulate the internet, nor even if such regulation is required. She doesnt even speak for all of mumsnet.
This strikes me as yet another of the almost constant whine about "There are bad things on the internet but I dont want to have to supervise or interact with my kids so you have to make it safe for them."
If people spent less time whining about some smut on the web and more time with their kids, joining in their activities and trying to learn about what was going on, this problem would pretty much go away.
Just like TV a few generations ago, the internet is NOT a babysitter. Ignorance is not a reason to make others spend time and money to solve problems.
As a parent, and member of Mumsnet (shamefully), I am happy to take full responsibility for what I see and do online and what my children see and do online. I do NOT want an unaccountable third party getting to choose what is or isnt suitable for my children.