The horror scenario

It’s interesting to see that the core concept of Infogalactic is Sir Tim Berners-Lee’s horror scenario:

I talk about the horror scenario of going to a candidate’s webpage and depending on who you were you get a different message and that is just marketing 101 for the political websites out there. So we need to rethink the way we have built society on top of the web.

But why shouldn’t people see what they prefer to see? Why should they be forced to see what Sir Tim, or the 512 Wikipedia admins want them to see?