The argumet that if it is good, it would exist already is at is essens a conservative argument.

No, it isn't. There is no law against worker co-operatives, so it's not a question about "economic model." Not a question of "political economy," just about one particular form of organisation and a no-issue.

Should all companies be "worker co-operatives?" Why, if somebody wants otherwise? I prefer liberal democracy, individual liberty.

And even if, there still would be the same finance, real estate and resource markets that would rob blind these co-operatives. Production organisation does not address the core issues of land and finance.