That's true but I think that winner-take-all markets exist in a large part because of the centralization of capital and how new capital enters the economy.
New money from the Fed flows into the system through massive institutions first; the money trickles down from the government to a few big corporations and then it trickles down to a few big private capital and VC firms and then it trickles down to a select few startups... VC firms collectively run an oligopoly; their main customers are big corporations so they don't have much interest in funding too many competing startups. The corporations which are funding the VCs don't want to acqui-hire too many of the same startups otherwise it gets difficult to justify their M&A strategy to shareholders.