Bernie won a couple states that never help determine the election. Then Biden won by a lot in swing states. If Bernie won swing states it would be different. He didn’t. His appeal isn’t and wasn’t as good in the specific places the Presidency is won.
It sucks because I picked him in both primaries. But the reality is Biden had broader appeal where it mattered. Any Dem candidate is going get 170 EC votes along the coasts. It’s between the coasts where the election is won. And Biden did better in all those places.