https://en.wikipedia.org/wiki/Open_primaries_in_the_United_States
" First, one party could organize its voters to vote in the other party's primary and choose the candidate that they most agree with
or that they think their party could most easily defeat.
Secondly, in the open primary moderates and independent voters can vote in either party.
This occurrence may dilute the vote of a particular party and lead to a nominee who does not represent the views of his or her particular party."
GREAT point!