Just like fascists, tankies could theoretically hang out here without getting the boot. It's just that genocide denying authoritarians cannot be tolerated in a tolerant, democratic society. The reason tankies and fascists get the boot is because they can't resist trying to bully and intimidate those that find their views abhorrent. They simply can't resist being terrible.

They're cultists with views that can't stand up to scrutiny, so they need use other tactics to spread their shit and gain power. They use the real downsides and weaknesses of democracy to argue we need an even worse system. Then they argue you actually hold the worst views of their enemies, even though they usually support exactly the same things that make those enemies bad. Tankies claim you're a free-market liberal for opposing them, when the countries they support are state capitalists. Fascists claim you're against freedom of speech, while they are always trying to ban ideas they hate. Some of them are misguided and believe their own lies, but others are just awful people.