In a reasonable country, we’d have a parliamentary system that enables more political parties, and in a really reasonable one we’d have preference style voking like Ranked Choice Voting (fairvote.org) so that extremist primary candidates wouldn’t control everything.
The main threat the GOP is using to force their caucus to vote for an insurrectionist Speaker candidate is the threat of being primaried by a MAGA nut job if they don’t toe the party line. Our system is built to reinforce a two party system, no matter how crazy one of parties is.