Comment: effective ownership is everything

You are trying to define a distinction that does not matter -- e.g., whose name is on the patent (the inventor) vs who controls the rights granted by that patent.

If the inventor owns the rights (for a limited time), then the inventor has the right to make a deal to exclusively license those rights to someone else, or a group of other people. That group can be shareholders, with the shareholders' representatives (company executives) brokering the deal. If you are going to prevent the inventor from entering into such deals, then the value of IP rights is radically diminished to the point where they fail to serve their intended purpose. (What is the point of limited monopoly rights if the inventor can not license them in such a way that the monopoly is preserved? Most inventors can not realize their idea by themselves -- they need an entity capable of making the design reality on a suitable scale. And they generally need to offer such exclusive deals to garner the commercial interest of such an entity.)

Also, if you prevent inventors from entering into employment contracts whereby inventions made on-the-job automatically enter the employee and the shareholders into such a deal, then the value of their employment is radically diminished. (Many inventors would not be able to invent much of anything if they did not have someone paying them to spend their days thinking stuff up and trying out ideas, and providing other resources that are required for that task.)

If you prevent companies from having effective ownership of IP rights, then you destroy the value of those rights. So either you do that, or you don't. And if you don't, then like I said, you are just changing the paperwork that they have to file in order to acquire such effective ownership.