Fair question, I suppose I didn't express myself clearly.
Firstly, I'd like to abolish the idea that "greenfield" and existing are somehow opposites. Greenfield projects take on a bunch of existing abstractions and complexities from all the stuff they are built on. Instead, these two terms are actually very similar, "greenfield" projects just chose to throw out one more layer than using the existing system. My argument here is that the dichotomy here is false, and that the two terms are instead a classification of degrees to which you abandon existing abstractions.
As I said, I understand that this is what you mean when you say greenfield, I'm not asking you to use different words. I'm asking you to pay notice that this is what you are saying. That you are explicitly not in a "green field" with nothing around you. You've thrown all the furniture out, but the building is still there, the walls are still the same color, and the windows are still overlooking the same parking lot.
This makes no sense to me... Greenfield projects have problems that legacy projects don't (What language to use, what framework to use, where/how to deploy, etc.), and vice versa (How do I design my feature with the existing limitations of the system in mind, do I need to to redesign a part of the existing system to get it to work, etc.).
None of that has anything to do with "Time thinking about the problem", nor does either one imply that its questions are easier or harder to answer in all scenarios. They're just very different questions, but some devs prefer dealing with the issues a greenfield project presents.
