I think it stalls more innovation than it encourages, and generally prevents new entry into a technology space, because the existing players have all the patents that a new player would need to get started. The fewer players you have in a technology space, the less innovation there will be, because “necessity is the mother of invention” and people don’t generally start working on an idea unless they are exposed to the problems of that field. In theory, a non-player could start a research shop and then sell the results of their research in the form of a patent, and this happens sometimes, but just as often the industry decides they don’t want to pay, and leaves the idea dead until the patent expires.
My pet example is the mosquito laser. They invented it at MIT, and showed that it could effectively shoot down mosquitos that pass between posts. The hardware costs were a bit high, but would come down drastically if someone mass-produced custom chips for it. But, the overall idea is patented, and currently held by a “think tank” licensing company, and no product has emerged. I can only assume that it is because their licensing demands are too high. I’d be happy to start my own company to build mosquito lasers, but I’m sure that their licensing costs would kill any profit from it, so I don’t. And so the world is left with no mosquito lasers for more than a decade.
If you want another extreme example, the 3D printer craze was kicked off by the expiration of a patent on the FDM process: https://www.fabbaloo.com/blog/2020/3/2/the-challenge-and-opp... The innovation in the 3D printer space probably lost 10 years due to that patent.
One possible solution to the problem, without throwing out the entire patent system, would be to create a mandatory licensing system with fixed rates. For example, if you know that your design is about 60% patented, and there is a law that says 20% of your profits have to be given to the patent holder, then you might be able to go ahead and make the product and still turn a reasonable profit. The patent holders would get paid something and the products would continue being innovated without these stupid wait-17-years delays. Also it would put less severe stake on the patents, so people could just argue out the details in court about who gets how much money without worrying that it was going to bankrupt a company or kill the product line.