That's a misinterpretation of parent's comment.

I think he meant fidgeting with pre made solutions hoping they will work, instead of having principled ways to craft things.

If SpaceX were to "plumb" as he meant it, they would use of the shelf modules and ideas for quick results. Instead they actually designed their rockets mostly from scratch (very rare in space, where it's often a rule not to go off what's provent to work).