They've never had the opportunity to make a play anywhere near the significance of the Clark play because they don't have a Joe Montana as their QB leading them to championship games. For a team to be propelled to greatness they need a great QB and an excellent HC. Clark would have never had the opportunity to make that CATCH if Montana didn't get that pass off over the out stretched hands of Too Tall Jones and put it where he had the chance to make a play on it. When Montana won his first SB Jerry Rice and John Taylor hadn't even arrived. He won SB's with different sets of receivers.
Most great QB's make a receiver no one would have ever heard of Clayton and Duper if they didn't have Dan Marino as their QB. Most of the receivers in the HOF had HOF QB's throwing to them. A lot of receivers reflect their QB and some of Romo's receivers seem to reflect him. They'll make great plays during the regular season but never come up big when it matters most. The type of impulsive, gunslinging QB Romo is can create issues at times with communication between him and his receivers. There was a heated exchange on the sidelines between Romo and Witten last season after a misfire on 3rd down. Romo takes a lot of chances and forces the ball at times. There's a trust factor I think this team lacks with Romo. We've seen that with some of the play calling like in NE in 2011 not allowing Romo to throw the ball to try and put NE away in the final 3 minutes.
We saw it in AZ later that season with Garrett again not allowing Romo to put the ball up after just making a big play to Dez to try and make for an easier FG attempt. Garrett is so afraid of turnovers he would rather rely on his kicker from 48 yards out. The great teams had trust in their QB regardless of the situation and in each other. Here's a quote from Amad Bradshaw on NFLN in 2012:
“You know what, man, I don’t see it happening,” Bradshaw said on NFL Network. “I don’t think they believe it, and they’re America’s team. It all comes in together. If the fans don’t believe it, the team doesn’t. They’re kinda doubtful with Romo.”