By definition, a system in which customers and workers made all the decisions would not be capitalism. The reason we don’t have such a system is that the system we do have was imposed on people by force and violence, starting with the separation of peasants and workers from the land and control over production. 400 years later, we have all become habituated to believe it is the only possible, viable system, just as earlier societies believed in the divine right of kings. And force and violence are still used to maintain the system and to disrupt and destroy alternatives when they spring up. Whatever negative things existed in Cuba were unquestionably made much worse by the actions of the US, for example; other examples abound. That has a chilling effect on people who might want to pose the same questions you do.
In the middle of this system, it is also very hard to create and maintain the co-ops and collectives and democratic enterprises you’re talking about. My own experience in a collective bakery was we had little money, our business model was not a good risk by the rules of the bank (“No boss? I don’t think so!”) so funding for equipment, advertising, etc., was really limited. It required long hours and less pay than if we’d all gone to work at a bakery. Nonetheless, it lasted for 15 years.
Today, 8% of Italy’s GDP is generated by co-ops and collectives. It is typically easier to set up such enterprises there than in the US or Canada, with some government assistance available. They also tend to be created in areas and sectors where the private enterprise (capitalist, for profit) model has failed. Local water supply systems are one example where people just got sick of the terrible results of the private system and set up their own. Mondragon in Spain is a collection of collectives that currently has about 75,000 people in it, running businesses ranging from retail to actual production.
To your point that the capitalist could be considered a middleman, I’m not sure what you mean by capitalist. Someone who supplies capital and expects a return on the investment? Someone with specific management skills or facilitation skills? Sales people? These are very different functions and some could indeed be simply another job, paid a decent wage, rather than “boss who also takes out a lot of money unrelated to the effort he puts in.”
So you’re on to something, and there are some examples of success!