Facepalm

Its not essential ,its just inevitable. Like most of the problems with capitalism, the problem is the inevitability of wealth consolidation that allows the purchase of power that allows further wealth consolidation that allows the purchase of greater power, round and round. Capitalism is an ouroboros, we are just in the stage where its about to finish eating itself.

Essential? No. It's ultimately just as harmful to an idealized version of the maximized productivity via competition dream. Smith and Locke both have quite a lot to say on the topic. Smith in particular makes a lot of points on how regulation is required to prevent capitalism strangling itself, which modern laissez-faire enthusiasts always conveniently "forget." This is the exactly wrong kind of artificial control by the ruling class that they did rail against.

It's what every capitalist does anyways because it's the easiest way to steal money, yes, and because every modern capitalist is trained to be that way through the ideology that has developed around an economic theory.

I'm not entirely sure about your take. If we say that this is fine and allowable, then you give a few large firms a huge lever to control the market with. If robinhood can limit investment to a specific stock, so could everyone, and at that point you allow them to decide the market through collusion, because you wouldn't need too many places to get on board to seal a companies fate.