It use to be that candidates were chosen in state conventions. Now savvy voters dont want party bosses choosing their candidates especially when they go out and vote in a primary and find out it was all a sham. You have a losing argument and your candidates poll numbers reflect that. Keep arguing anyway but you wont get your candidate the presidency by saying stealing delegates is okay.
There is no “stealing” taking place. The presidential preference vote means nothing after states become unbound on subsequent ballots. The votes for the delegates is what counts. Cruz is competing to get his delegates voted in and to persuade the delegates to support him once they are unbound. There is no other way to play the game. Those are the rules. I can guarantee you Trump will be trying to persuade the delegates eventually, but his mistake is he’s been lazy, cheap and inattentive and let Cruz start a lot earlier.