That's not a fair assumption since there are no downvotes. If 20% of people really like something, and 80% hate it, it could still very easily own the front page.
Regardless you're focusing too much on the numbers I threw out there solely for example. The point is that without down votes its entirely possible for a number of similar items to hit the front page even though a majority of people dislike them, thus invalidating the idea that a number of similar items on the front page means a majority of people find them useful.
That's ridiculous, of course there are downvotes. In fact all it takes is a very small minority to flag something and it goes off the site. This happens all the time.
A flag and a downvote are two very different things. If there were downvotes I'd use them all the time. There are flags and yet I only use them rarely, for spam, or something off topic, or with an editorialized headline, etc.
Flags aren't meant to express dislike, they're meant to express something being inappropriate. Lots of stuff I dislike is appropriate here.
