Let's not understate the confounding nature of that last play:
1) Spurs get the rebound with 20 seconds left
2) DeRozan holds the ball for that ENTIRE duration - never even thinks about passing to setting up a play, with the possibility of him getting it back anyway
3) DeRozan settles for a fully contested fall-away jumper around 20 feet from the goal, with a Belinelli-esque lean to the side, that is BADLY missed
I absolutely concur with the OP in that the other players were sunk in OT because of that.
That Derozan play was the definition of iso-ball, hero-ball, low IQ at its highest.
And to note - I don't blame DeRozan here. He didn't want to be in San Antonio, and the Spurs sure as wouldn't have signed him to a max deal under any hypothetical scenario. I believe the FO sought to punish Leonard by sending him to Canada instead of California, and this guy was the best they could get back.
What's truly tragic is we are probably left with DD for two more seasons with his untradeable contract, and Leonard is on the Clips this July.
We (the Spurs) got our just desserts for the petty play to banish Leonard. Something poetic about that.