He can call himself whatever he wants, but that doesn’t make it true. Being a member of the Democratic Party requires party membership. That’s a fundamental issue. The reason why some people, including me, have issues with Bernie is that for decades he attacked the Democratic Party, and then when it suits him, he decides to identify with the party without ever becoming a Party member. There’s a reason why parties exist, and saying that they are fundamentally worthless disregards very important organizing that happens down ballot. There’s a reason why parties build coattails, and why there was no Berniecrat wave.