Seems more of a moral hazard of government intervention than of ventures whose economies of scale demand large market cap to most economically serve customer needs.

"Most economically" can be bent to nearly any purpose, there's almost always a cost-benefit to owning more of what you do, or externalizing costs onto others. It's not enough of a reason, and it's why laws restricting private behavior to serve the greater public exist.

Which is very nearly the only reason to have governments: forcing restrictions that lead to better results in aggregate.

(malicious control is another reason, but you kinda can't argue public benefit there)