Losing the House, Senate, presidency, governorships around the country and state assemblies: you better believe that your leadership is the problem.
I don’t think that Bernie has made any points about the two parties being similar.
The indisputable truth is that he campaigned hard for Clinton after the primaries and urged his supporters to vote for her. That doesn’t sound to me like someone who thinks the two parties are the same.
The idea that he is somehow to blame for the political shit show that is the Democratic party is a willful denial of reality.