I feel like tankies and anarchists proliferate on social media so well (relative to communists) because it's simple for them to comment something "fresh" on a piece of news whereas communists say the same correct things over-and-over and just get dismissed as class reductionist or champagne socialist. Tankies (and paradoxically anarchists) get to pick a side in the Russo-Ukraine invasion and vomit a myriad of poor excuses in defense of their position while communists can only advocate for revolutionary defeatism.
People classify them as libleft and authleft but in the end they both carry water for capital. Anarchists are perhaps more articulate than libertarians but they both fundamentally agree that it's the right ideals/laws that make society prosper rather than the structure of the economy. Tankies think communism is when the state has a monopoly on labor.