I do agree that’s it’s a bit of a “no true scotsman” fallacy, but on the other hand many states call them themselves “democratic” without being so. At some point you have to look at the actual ideology and see if the state lives up to it. And nearly all self-proclaimed communist states simply do not. But it doesn’t really matter if they are “real” communists or not - they are not what a lot of communists/socialist believe in and support.
I can agree that getting people out of poverty is cool. But tankies generally don’t practice “critical support” of CPC. They practice unwavering boot-deepthroating. I have never heard anyone from that side of the left say (or acknowledge) anything negative about CPC. Any critiques put up is usually dismissed as “CIA propaganda”.