[Jiro]

Because the opportunities to profit from open source are limited, and mostly already taken. Any new company is likely to be either a fraudster, or a zealot and an amateur. Neither of those categories is likely to produce something good. (And the open source field specifically is full of zealots and amateurs that don't exist in other fields. And also fraudsters preying on the zealots and amateurs.)

Furthermore, a lot of business models require convincing other people to support you, either through investment, or through getting a larger share of your company's budget. This filters out many incompetent businesses, but since open source is free, the filter is poorer It's like asking why the average book in a bookstore is better than the average book on Amazon Kindle--if you don't need to convince a publisher to spend their limited resources on your book, there's one less filter for bad books.