You mean like the holding penalty the Steelers got in the endzone resulting in a safety which wasnt a holding penalty? The one which gave the ball to Arizona where they scored 2 plays later to take the lead? Selective memories at their finest. The "darling" argument is only one used by jealous fans of other teams I find.
It has more to do with the Steelers being better talent evaluators, drafters, and having ownership which knows what it takes to win than a lot of other teams. It's no secret they shunned high priced free agents, and built through the draft....and by consistently winning other franchises started copying their methods. As a Steelers and Rams fan, until recently, the differences in the two franchises was night and day...... and winning starts at the top by building a winner more than anything. Luckily for me, both teams are looking up this year...and the Rams now have the pieces in play from an organizational standpoint to start a winning tradition like there has been in Pittsburgh.