It could slow down progress.
Who beside the open source community develops new features if they can be easily copied?
You think open source never develops new features?
The only thing that made commercial software more innovative is most developers never had time to build and maintain a big open source project without support from their job. Now we have agents and it takes a lot less time to implement your ideas. That means slop filling up GitHub, but also that people who came up with good new features can make them real in their free time.
ReSkate is a good example, it's a project 90% coded by AI but the people working on it are passionate and most of them are experienced game modders. They know what made the old Skate games special and wanted to bring it back to the new one. Now it's better than vanilla Skate 4 and has tons of new features never seen in the OG trilogy. That project would never be possible without Claude taking care of the hard and boring RE work.
AI's pretty good at copying features even when it's closed, or online.
Not perfect, of course. All that hype about the vibe-cloned Adobe suite is, today, hype. Next year it might not be, though that depends on questions like "will investment bubble pop?" etc.
But we are at a level where, if you can describe a feature or process well enough to test it, an LLM can develop and optimise for that feature/process. That creates opportunities for businesses to have custom just-for-them business software, which nobody copies because nobody outside the business even bothers to learn exist.
Why use proprietary software when there is opensource one ?
Is your theory really that closed source software will just stop being developed? I can't find another way to read that, but you can't think Google is just going to give up and shut down, right?