If we define working people as 'employees' (as opposed to 'employers', who we call capitalists), then those who work in a cooperative actually are something else. They don't fit into this scheme, one could call them just 'free people'. If we look at the history of labor movements, they seem to aim for either 1) social democratic reform 2) sovjet style 'socialism' (replace the capitalist bosses with 'socialist' bosses) or 3) if workers actually try to achieve libertarian socialism, they fail badly because they lack the support of the masses and the experience how to govern the economy (like in catalonia). Therefore, shouldn't we rather put our hopes for socialism on the people working in cooperatives than on those who would like to, but never do something for it (except waiting for a revolution that will never happen or fail badly as long as the masses of people stay employees)?
I am not clear on your critique of libertarian socialism, but I do basically agree that we must learn from the history of the first efforts to systemically go beyond capitalism (the experiments in socialism in the USSR, PRC etc.). That means learning from what those experiments achieved and from their failures. Thats what an earlier generation did in assessing the achievements and failures of the Paris Commune of 1870 and various other revolutionary, anti-capitalist upsurges. Just like capitalism's early experiments in the transition out of feudalism, so socialism's early efforts to go beyond capitalism must be critically interrogated. That many failed did not prevent the eventual demise of feudalism in favor of capitalism; and that many early efforts at socialism failed likewise tells us little about socialism's ultimate prospects.
I also agree that the current movement to revive cooperatives and especially worker cooperatives is an extremely important and promising form of anti-capitalism. It offers a mass-based, bottom up kind of socialism that might avoid the mistakes ands failures of the state-heavy earlier experiments.