What aspect of GOP primary rules allowed trump to win nomination?
The main thing was the preponderance of Winner-Take-All primaries, which allowed him to, for example, win 100% of South Carolina's delegates with 33% of the vote and build up a lead which eventually became insurmountable that way.
However, more so than the primary process itself was the pre-primary process in which the Establishment coalesced around Jeb Bush, who then proceeded to flop spectacularly in the election, but yet who was unable to drop out due to his commanding lead in fundraising and endorsements. The murder/suicide of negative campaigning between Bush and Rubio helped him too.
