this poll is very interesting, cause we can see than a two-round system open doors for actual "minor" parties
we can see that they are "minor" only because the FPTP actual rule.
In practice is this not really the case, though. Most of the former Confederacy has a second round for elections if nobody gets a majority in the first round, and Louisiana, California, and Washington have some version of the jungle primary which is basically the same thing. In none of these states do you see minor parties really taking off at all.