What appears to be "blind support" is people desperately clinging onto what tiny bit of representation they have. It's sad for both sides. It's Stockholm syndrome mixed with political pragmatism. It sucks, but the current political landscape in the US has entrenched itself so deeply in a local minima that people feel like they have to work backwards to make progress. Just see how any discussion of a third party is seen as a psyop to get that side to have a spoiler effect.