They kind of are, by painting them as the exact same and not noting the very real differences between them you are in a sense defending the Republican party.
Especially in the context of this conversation.
That's not to say that the political system doesn't deserve a level of scrutiny, it most definitely does but the hard reality is that there's no reform that doesn't come with participating in it on some level.
I think what weakens the case is that we've had a lot of progressive Democrats that have demonstrated real change and to ignore that is not just defending the Republican party but deminishing the very real work by people who want that change.