You kind of wreck a decent argument with hyperbole, that argument being the "death march". Not many of those of late, but then not much of an option drum major of late, which makes the marching difficult. (Before anybody goes off I give you Marshall's ability with the ball; an option runs off the QB's ability without the ball.) But about this offense thing. First, Swinney and Clemson have diligently, single-mindedly, don't spare the horses, built a national power in the same time Johnson has been at Tech. It is not a knock on Johnson that he has not, since even a Tech engineer cannot build a Jaguar from a Model A parts kit. GT is what it is, apparently what it wants to be; Clemson wants something else and is willing to pay for it. As a longtime sidewalk fan, I am good with Tech's position, but if alums are not, then make noise about what level of support you demand. As long as it is honest I'll be good with that, too. So, yep, in the last two years while Clemson was in the NC twice and Georgia once, Tech scored 10 and 7 points against Clemson and 7 and -- what's this, 28? -- against Georgia. In 10 years of Johnson's offense against Clemson, it scored, counting backward, 10, 7, 24, 28, 31, 31, 31, 13, 30 and 21 points. That somewhat exceeds your "repeatedly" fails to score more than 13 points. That using "absolute" comparison will get you every time. (I am aware that of the 28 scored in 2014, 14 were on two horrendous decisions by Clemson QB resulting in two glorious pick returns; so sue me. Sue us.)
So yes, as Clemson has built its world class defense, rivaling Alabama's (it's most recent playoff loss to Alabama included two Alabama TDs off Clemson's mistakes, too) Georgia Tech has found it tough to score, a difficulty encountered by most on Clemson's schedule. Throw out the last two years and we've averaged about four TD's a game (26 points) on them. That to this inexpert eye is pretty good offense against a P5 opponent. But you know what? Get those 35 and 56 point games and it spoils us. It ain't that easy.
Now, you done made me go and do research which I hate and my head hurts.