The people throwing around "tankie" like this are nearly universally unaware of even their own stated political theoretical background. They hold these views because they have absorbed liberal anticommunism, including the anticommunism that their ideological predecessors absorbed and published about, like anti-Soviet propaganda that some US anarchists embraced in the 30s. Generally speaking, their complaints are not based in any coherent criticism that is actually rooted in political theory. So their entire complaint is often as ridiculoys as labeling people as authoritarian and leveraging this as a thinking-terminating cliché and throwing a tantrum when the absurdity is pointed out.

For example, there are several comments in that linked thread that are blanket declarations against hierarchy and calling themselves anarchist. There haa never been an anarchist collective that actually did anything that did not have hierarchy and being blanket opposed to all hierarchy is not, historically, an actual anarchist position. Instead, they have historically embraced a critique of hierarchy and seek to dismantle those that are unjust and most oppressive is the common theme, e.g. fighting capitalists and capitalism.

These are the "anarchists" that are just liberals with an aesthetic, not our comrades that work to dismantle oppression. They are appropriators of the tradition and are even hostile to it when you aak them to read about it. Hell, they complain about the Red Army's suppression of Makhnovschina but get angry when you suggest reading publications by those in the Black Army when it doesn't completely support their anticommunism.

They can be reached but I've only seen this irl when actual anarchists correct them.