when strong third party campaigns force rival parties to cater to the independent vote to get over the 50% hump.
I’m not saying 3rd parties have zero influence, but they just don’t succeed frequently enough for it to be called fair. The spoiler effect is far too strong for that to happen.
we absolutely do have factions within the main two parties that have regionalized and polarized constituencies that are fighting for control of the national party apparatuses.
Absolutely. But because of the spoiler effect, the two parties are held together with glue. Reforming our electoral system would weaken that glue, and hopefully fracture them enough to make a difference.