Because you're seeing what you want to see, being results oriented with micro-decisions. You don't lose a game in which you're leading by 19 by 9 just because Pop chose to go with a suspect line-up for a bit. Let's look at the 3 point stats from that game: Spurs: 5-18, Denver: 10-24. 15 point difference. Game 4 home loss: Spurs: 5-17, Denver: 15-31. Tonight: Spurs: 7-24, Denver: 14-33. Absolutely slaughtered from 3 in the losses, but yeah, this series isn't about the Spurs lacking 3 point shooting vs. Denver

. It's about Pop and playing Mills and Belli (who admittedly suck) too much. Spurs are outgunned, and no amount of counterfactuals would've changed things.
I get it, it's easier and more cathartic to "blame" individuals after a loss rather than just admitting we're bringing a mid-range knife to a three point gun fight.