That's how it's supposed to work, finance as essentially the servant of productive industry, increasing liquidity and lubricating the economy. But owners of finance capital, like any capital, want to employ it in the maximally profitable ways, not "just" run a service industry, so also try to get the upper hand where they're in control of markets and the direction of businesses, with owners of productive capital essentially servicing them. Who actually is making decisions is a bit more complex than "a war", but I think there is a constant bit of power struggle, at least, with non-finance businesses wanting finance perform a service role, and finance not wanting to be boxed into one.
Someone needs to provide productive capital in the form of equity. If that equity wasn't tradable, fewer people would be ready to provide that capital. If there was no financial capital, there wouldn't be any credit either.
So without much equity capital and without loans everything would have to be funded out of cash flow. There would be no large projects, no investment in future demand or longer term infrastructure, it would all be hand to mouth.
Also, in many cases that cash flow would eventually outgrow what a company or individual can productively deploy. Without creating financial capital out of that cash flow, ie lending the money to someone who can productively deploy it, that capital would be stuck even though it could be used productively elsewhere.