This seems to be to be another example of a situation where the message is far more important than the messenger - the candidate - who carries it. The first of these was Cannon, in Utah-3. His defeat in the primary might not actually produce a better candidate, but it WOULD deliver an absolutely critical message to the leadership that they have been flaunting their power and flouting their party.
Chaffee is the most egregious example of the same problem in the Senate, and kicking him out would be a positive benefit to the Repubs, and no loss at all.
You are absolutely correct, and succinctly so!