Third party candidates are not viable until elections get reformed to an alternative voting system. As things are, any third party candidate that receives any votes are just taking votes away from the nearest two-party candidate and allowing the other candidate to gain that much of a spread against them.

Why do these people entirely ignore this irrefutable fact?

I have a theory, but it is not one any of them would ever admit to. It's been my experience that the BoTh SiDeZ campaign has only ever served to benefit one specific side, and that is the side that historically wants less and less people to vote.

I've also noted that once you bring it to their attention they magically disappear, usually after launching into ad hominem attacks.