It's hard to argue with the OP. Pretty much all the NBA dynasties of the past 50 years have had drafted players at their core (Russel, Magic, Bird, Jordan, Kobe, and potentially Curry).
That said, those same teams landed foundational players through free agency. The Lakers aren't winning their three-peat without signing Shaq, and Rodman helped fuel the Bull's second championship three-peat (1995 - 1998)
I think there's a consensus on this board that if the Cs land the No 1. or No 2 pick, they should take their chances with drafting a potential franchise player. But talent-wise, this year's draft is very shallow, so anything outside the Top 3 should probably be traded for a proven star that can carry this team.