America since its inception has been dominated by a two party system because our electoral system makes that the optimal way to play the game
So the only way for 3rd parties to become actual contenders is to replace first past the post with RCV
Do they refuse to accept this fact or don’t actually want to succeed?
EDIT: please read the top 5 responses before responding, I have seen too many instances of "libertarians are just republicans"
The Libertarian party platform does call for "alternative voting systems," which I would assume includes RCV.
The issue with libertarians (small L) here is that the majority of them are extremely disorganized, and the Libertarian (big L) party is extremely weak and ineffectual because of it.