Diehard Democrats need a scapegoat because without one they are left with the painfully uncomfortable realisation that the DNC exists in a parasitical relationship with the GOP and that, in a shocking number of situations, their party would prefer a Republican victory because it provides the Democrats with huge opportunities for shifting further to the right, for preferencing the interests of capital instead of needing to make small concessions to the working class, and of course for fundraising.

So naturally it's the tankies and the trans people and the Russian bots who are ruining the so-called left. They need this to be true in order to diffuse the cognitive dissonance they experience by being a Democrat supporter.