> negative externalities like pollution, over-harvesting, misinformation, or antibiotics misuse.
Not disagreeing, because the point is true. However solutions for most of these have been found
a) over-harvesting : only a problem in a non-fully-privatized situation (in other words, the more government involvement, the more you have this problem). This one is actually an argument FOR capitalism.
b) pollution is also a tragedy of the commons thing, and could be solved by privatisation. Of course, in the real world that presents some challenges.
c) misinformation : this is not a problem of capitalism at all. Or rather, it's a problem that solves itself under capitalism (though not necessarily to people's liking). For example, insurance can fix this. Under central planning systems, every one I've ever seen, the problem is not so much misinformation, but the total lack of relevant information at all (e.g. employing the mayor's daughter in your management structure gets you the contract for city IT, good luck finding that info. Oh and if you're an idealist : good luck preventing that from happening).
d) antibiotics misuse : well, on one hand this is happening partly due to misuse. However, where do you have any data whatsoever that it wouldn't happen without misuse ? As far as I can tell antibiotics resistance happened even before WWII, when we were definitely not wasting antibiotics. At any rate, the ship has sailed and it's a sunk cost at this point. We should not waste money and resources fighting it, as even massive effort can only slightly reduce the rate here, it can't fix it.
(one theory I found is that what's happening is simply that we are effectively raising the price of new and therefore working antibiotics, dampening their use, until a balance with nature is found. Sadly, it is blatantly obvious that in order for this to actually happen, the vast majority of the sick would need to go untreated, so there simply isn't a good solution, capitalist or government)