Im not talking about the paper but the actual research, the money the scientists needs to pay to the publisher is normaly covered by the employer.

Yes it makes sense if your goal is improoving the worlds knowlede and there are a lot of open knowlege platforms and open papers.

But research is expensive and scientists need to bring food to the table too. Someone needs do pay for all that and whoever pays can decide where the results go, if an aerospace industry company is researching on a new material, they do that because they hope to make proffit in the future.