I do hear the "scale" concern, and it's interesting to think about it. I.e. for me, it immediately pops the question "why is scale a problem for common ownership, but not for individual ownership". I suspect - without having any proof - that scale is the thing that makes the transition impossible, not that it's an inherent problem for community property itself. Practically, the outcome is indeed the same - if you can't safely transition, the end state is impossible, even if it itself would be a stable state.
This also raises the question of democracy & unequal ownership as a possible stable state - Plato was certainly concerned enough about it, and history has done nothing to discourage that belief since then. There are plenty of rather deadly examples of failed non-communist states.
If nothing else, your comment (and the subthread in general) has lead me to a rather interesting paper: "Social instability and redistribution of income", by Josef Falkinger. https://www.sciencedirect.com/science/article/abs/pii/S01762... (Yeah, as usual, paywalled. Elsevier)
It's a deliberate attempt at modelling outcomes based on income distribution - which I think attempts to get to the heart of the "impossible" issue. It only tackles income, not wealth, but there's a rich set of references :)
We also have repeated instances throughout history of groups claiming to try to implement common ownership, and instead killing millions and installing tyrannical governments (see: most communist revolutions), of consistently larger scale (orders of magnitude) than the successes.
Historically, it's far more probable that such a common ownership experiment will result in death and tyranny (and not actual common ownership!) than a success - and, given the relative difference in scale between the successes and failures, there's a strong argument to be made that as the scale goes up, the probability of tyranny goes up.
This is one of the justifications for it being impossible in a practical sense (yeah, it's annoying that there's more than one definition for "impossible"). It's a fact that power attracts corruption, and it's also a fact that planet-level-scale common ownership would require more power to implement than any government has achieved so far. So, while not "impossible" in the hard-science sense, it's improbable (with a correspondingly large chance of a catastrophically bad alternative) to the point that it's not reasonable to attempt.
That said, your comment is a measured and thoughtful answer to a potentially-inflammatory topic, and I hope that my response is equally thoughtful.