I agree with you that Marxism is flawed, that as you say it doesn’t account for human nature.
But: There's no additional overhead to "seize the means of production" vs. any other system of governance and organisation, given that corporations, money, ownership, and the law are all things that any functioning system of government controls anyway, regardless of if they want these things to be collectively owned (/nationalised) or privately controlled.
Now, my former partner who is a self-identified Communist of some kind (I can't remember which kind), she wants to abolish money, and abolishing it rather than using it would need quite a lot of extra effort.
> How do you allocate resources and labor fairly?
I believe the general claim here is "democratically". This doesn't really work too well, but on the other hand, neither does letting people accumulate so much money they become the de-facto leadership with the carrots and sticks of "I will move my business to whoever has the lowest tax/cheapest labour/least expensive safety requirements".
Consider also that normal people are nowhere near as carful with language use as you or I may wish; some of the people you're worried about may be identifying themselves as "Communists" in the first place only because they're exactly one step to the left of the Democrat Party's Overton window while also repeatedly observing the US Republican party describe the Democrats as "socialists".
(Conversely, my former is one of the people I expect you to be correctly worried about, as she agreed with my assessment that she was to the left of the Cuban communist party).