I always find this opinion infuriating. It's a liquid fueled rocket, we've had those for 50 years, so it's not cutting edge! It's like saying a modern Formula-1 car isn't cutting edge because we had the Lotus 77 40 years ago that looked a hell of a lot like it.

You have no idea what parts of it are or are not cutting edge. I guarantee you many of the parts and pieces in the rocket required pushing boundaries. All the little bits of material science, modern computational analysis, and advanced manufacturing techniques are cutting edge.

Eh, developed by/for the Air Force, e.g. the mid-50s Jupiter used RP-1/LOX. For that matter, Mercury and Gemini used Army and Air Force rockets for boosters, it wasn't until Apollo that they used purpose built civilian rockets. The gas-generator design of the rocket engines goes back at least to the mid-50s in the USSR, not sure when it was first used in the US, but various Saturn rockets developed for Apollo used that design.

They're using cutting edge stuff here and there, e.g. friction stir welding, which is a good match for the long seams in boosters, but mostly its organizational, and clean slate, not starting with a military rocket which is developed for and under different constraints. Or explicitly (Apollo) or implicitly (Space Shuttle and beyond) as a public works project, where cost is secondary to employing a lot of people.