What about looking at it the other way around, neither Linux nor PostgreSQL is a commercial product, never were and never will be. Many people create commercial products on top of them, and that's OK, it's allowed by the license. Even Redis started as a fully open source project. But then it was sold to a company, and company cares more about making money than taking care of open source product. If you are a small company, and want to create an open source product, that's only free for personal use, just say so up front. Don't try to pretend the product is something else. It's really not about size, it's about motivation, and the motivation of a company is always making money in the first place.