There are often a lot of steps between a discovery (or even a patent) and commercial viability. Patents make it easier for the companies to raise funding to do that work and move from theoretical or small scale to an actual product.

Also you could argue that patents are open access. The whole point of a patent is you give a complete summary of what the invention is and how to replicate it (with a level of detail that would allow someone knowledgeable in the field to recreate it) in exchange for a time limited legal moat.