I didn't understand either.
I don't let thumbs up and down affect my viewing. This is a choice in the PREFERENCES one has - both for Whole Threads, and for Single Posts.
In preferences, you can Collapse unpopular topics - or choose not to.
Me, I don't let others' decisions affect what I read.
I do figure though, for the website in general, that it is a useful tool as a clue what to look at, for a new person.