Absolutely correct, IMJ! I know several people who say that Bernie would have had a better chance against Trump than HRC (well, they used to say that when polls were closer). I disagree. As much as Clinton is disliked, the real divide is political and partisan, as you write. Bernie, being further left, would have had a harder time winning the undecided and independent voters. Additionally, I’m convinced the Republicans had devastating attacks in reserve against Bernie, all based on his left activist past. We haven’t heard any of that because they WANTED him to win the nomination, knowing he’d be far more vulnerable.
As a wise friend said, “if they could make John Kerry, a war hero, look like a coward (with their false swift boat attacks) imagine what they would do to Bernie.”
People may read that and think I’m advocating that Dems only nominate centrists. I view it as nominating only candidates who can win. As Hillary will.