> Not counting the years ...
Never knew a capable/competent developer who didn't spend years.
Unix, C, etc.. constitute other historical examples of having been built in a very short time apart from Linus's git.
With enough competence, it boils down to an exercise in organizing discipline and first principles derivation. As I have mentioned in the past, skillsets at sufficient granularity are transferable across domains.
What you said would be true when looked at each different project as a separate domain, but real world is rarely a collection of isolated domains.
To put that in perspective, our app SlypBusiness has memberships, products, services, gift cards, privilege cards, etc. which all look like different domains to a user but is fundamentally the same primitive instantiated differently.