Bollocks, quite frankly.
If you were to put forward a specific argument which I didn't think cut any mustard, it would be a complete waste of time and attention to reply, "Ah, well, you're a capitalist, and I don't agree with that, so everything else that might be related is worthless".
You're not a capitalist "some of the time". But I'm guessing that doesn't mean you're happy to abandon it the rest of the time, eh?
Capitalism and communism are not actually counterparts. Capitalism is an economic system. Communism is a social, political, and economic ideology. It is a combined vision of all aspects of society advocating for a utopia of absolute equality.
Why not? You have fanatic ''small government!'' advocates who want to give the government full control of people's bedrooms. And you can have ardent realists who might agree that some viewpoints of liberalism or even Marxism have a lot of a lot of merits.
Systems and peoples are too complex to be one thing all the time.
Real systems and real people are too complex to be all one thing. The imagination of a utopian idealist is not subject to the the rules of reality though. Of course there are reasonable points put forth by members of any ideology, and ideas mix rather fluidly, but an proponent of a "classless, stateless society" is not going to compromise on that. It is an absolute and all-encompassing demand.
There are many political arguments that come down to the question of how much government should involve itself in something, and how much control should be left to individuals, and it is common for people to put political groups on a sliding scale of how much involvement they advocate for, with small government conservatives one way, and libertarians a step beyond them, and then progressives the other way with socialists a step beyond them. And in some ways that can be a useful exercise, but some ideologies don't fit on that scale. Communism isn't the next step on the line graph, it does not fit on it at all, it's not maximum government involvement. Communism is "there is no government", but also simultaneously "no responsibility should be left to individuals". In the ideal world of a communist, the societal paradigm which we try to balance limited government against meeting people's needs is entirely erased. That is an argument within the worldview of liberalism, so it needn't even be considered.