Seize the means of production comes from a conceptually separate part of anti-capitalist critique then workers' control/workers' self-management. It is common to conflate these two strands of anti-capitalist thoughts. It is technically possible to have common ownership of the means of production without workers' self-management and workers' self-management without common ownership of the means of production. Universal worker coops only requires abolishing wage labor not private ownership @memes
On the part of labor. No matter how causally efficacious capital is. It can never be de facto responsible for anything because responsibility is imputed through the tools back to the workers using them.
A better case for worker cooperatives is just pointing out they satisfy the moral principle that legal and de facto responsibility should match. The workers are jointly de facto responsible for using up the inputs to produce the outputs, but in a capitalist firm, the employer holds sole legal responsibility for 100% the corresponding legal claim to the positive and negative result of the enterprise while employees receive 0%. In a worker coop, this mismatch is corrected
The employers' claim extend beyond a cut. They solely appropriate 100% of the whole positive and negative product of the firm while employees as employees have 0% claim on the whole product
What you are talking about is called social capital accumulation, which is a problem in any system.
A justification for worker coops is the moral principle of assigning legal responsibility to the de facto responsible party. In an employer-employee relationship, the employer receives 100% of the legal responsibility despite the employee being inextricably co-responsible. This violates the aforementioned principle
It depends on the material conditions what specific action would be required. For example, the legal system could abolish the employer-employee contract that violates workers inalienable rights to democracy and to appropriate the positive and negative fruits of their labor. Then, the contract could be reversed so that labor jointly hires capital rather than capital hiring labor. Amazon, in particular, has other issues that should be addressed, but we can ignore that for now