This isn't really accurate, from a Marxist perspective. Marx advocated for public ownership, ie equal ownership across all of society, not just worker ownership in small cells. This isn't Communism, but a form of cooperative-based socialism. There are groups that advocate for worker cooperatives, but these groups are not Communist.
Essentially, the reason why cooperatives are not Communist is because cooperatives retain class distinctions. This isn't a growing of Communism. Cooperatives are nice compared to traditional businesses, but they still don't abolish class distinctions. They don't get us to a fully publicly owned and planned economy run for all in the interests of all, but instead create competition among cooperatives with interests that run counter to other cooperatives.
Instead of creating a Communist society run for the collective good, you have a society run still for private interests, and this society still would inevitably erase its own competition and result in monopoly, just like Capitalism does, hence why even in a cooperative socialist society, communist revolution would still be on the table.