Since capitalists can be singularly focused on financial gain, markets which don't have some mechanisms to prevent collusion and other forms of corruption quickly become something other than free markets too.

Given the need to some kind of enforcement agency, mechanisms, and taxes to pay for such governance, all of which I consider socialism to greater or lesser degrees, I don't see that truly free markets are possible without socialist aspects.

If you and I were to make trades, that could be a truly free market, as it would preclude all of the problems I mention. Broader public markets can't though I think.