This. It explains nearly every move the team makes. The Spurs run their team differently than most, and while many give all the credit to Tim Duncan, I can't do the same. He deserves the lion's share, but I think Tim and Pop together (with RC too ofc) built the core of the system, a long-term strategic way of doing things that Pop has stuck to even after Tim retired. So while many want the Spurs to turn their roster over more and stop re-signing their own guys so often, I don't have a problem with sticking with what has worked and is in fact still working.
It's like a family business that refuses to pay as little and charge as much as they can possibly get away with, instead choosing to focus on keeping key employees happy even if it means overpaying them, and not chasing every penny of profit at any cost.