Earlier quoted context omitted.
Surely this won't make those considered stupid any smarter. Why shouldn't someone less intelligent be allowed to read and interact with an intellectual conversation. It's not that easy to group people in such ways.
It's not about segregation, it's about content promotion. Why should content-promotion algorithms be intelligence agnostic?
Because a "stupid" person might find the same thing interesting as a "dumb" person, hence the upvoting model. People who are inclined to agree are just as inclined to upvote these items, promoting them to a position where other people can consume said content.