This is true, but it's one sided and missing something very important.
Having powerful, well funded groups make products out of structured data also had several large, positive effects. The schemas became more practical for addressing the needs of real people. The volume, quality, and consistency of structured data on the web went up. The accessibility and usage of structured data went way up. Many useful products got built that probably never would have emerged without the corporate efforts.
You do a good job of highlighting many down sides to this, which are also true. But if you don't bring up the good sides, people will accuse you of cherry picking. If you tell both sides, they'll argue why the benefits outweigh the drawbacks.
So, I think it's worth disentangling the threads of not just what they did but how they did it. Funding products and product-oriented data curation was positive. But they had ulterior motives, which is why they designed the systems to be closed, proprietary, and unaccountable. It didn't have to be like that. Could we do it differently, avoid most of the harms, and still reap most of the benefits?
I like your vulgar data vision, but it doesn't address this key point. How do we get high quality useful tools without handing everything over to a rich corporation? We do need an effective model for organizing and funding the vulgar efforts so they can compete.