A gun is just a construct, and so is death when you shoot someone in the head with it.
(Btw I'm not arguing for capitalism here. Just providing a critique.)
Incentives shape behaviour and for the most part determine outcomes, and I think what a lot of MLs assume is everyone is as intelligent and measured as they are, when they're statistically a minority. MLs assume society will function exactly the way they imagine it should because they project their own intelligence and motivations onto everyone, and primarily talk about communism with other MLs who are predominantly on the smart half of the bell curve. It's a well known thing in psychology called the "curse of knowledge" and cognitive egocentrism. A person with a deep body of knowledge (an expert) projects their own expertise onto others, and smart people do the same thing with intelligence.
The majority of humans alive are barely more intelligent than apes, except they do a good job of acting like they're way way more intelligent... You need guard rails and checks against a highly motivated, charismatic idiot with no empathy from using the entire structure you've built for their own gain. What incentive do they have not to? Especially if they can say all the right words and slogans to appear like they're just like you, only to gain power and abuse it where nobody can remove them.
The unfortunate part is communist power structures and committees get captured by bad actors the same way capitalists capture regulatory bodies and law makers. It's humans capturing human made institutions and I don't think it really matters the ideology behind what they say is happening. What's important is their actions.
We're also unfortunately still hardwired to be tribal. We think in terms of family, tribe (friends), community (acquaintances), town/city, province, nation .etc where as each circle grows it gets more nebulous and detached from our identity and who we are. Everyone's a communist for their family, some for their friends and communities. However most people reach a point where they go "yeah, fuck those guys." Where the majority of people reach the cognitive limit of what they care about. So your example of a tribe leader works really well as maybe a mayor or something at most, but falls apart when that good tribe leader is competing with bad actors who want the central committee spot far far more, and are willing to do viscious shit to keep the good guy out of that spot. At the same time the good tribe leader has good intentions, but feels like they have a stronger direct impact at a lower level while being shut out of higher office.
It's like how democracies eventually end up selecting for candidates who get elected, not candidates who will do a good job. Those are vastly different skill sets.