Nicely written Steve.    Political operators don't have their job to tell the truth about their employer - whichever party it is.   Their job it to win elections so that campaign 'investors' will be rewarded.

The professionals persuaders know exactly what you have pointed out.   They know the detailed policy is not as important as great sounding policy with 'deniability' if their candidate is elected.    The winner between the wonkish and dispassionate Hillary and the hot Trump, (who has the advantage of having no record at all in politics), is his ability to promise anything and sell it.   

Pres. Trump can Sell and he's figured out the emotional triggers that work on prospective buyers and uses those insights to close the deal.   The salesman seldom takes responsibility for the real performance of the product or service if it fails months/years later.

I don't think President Trump had any strategy for delivering on campaign promises.