From things like what Audacity did: adding spyware or other bloat that serves the company rather than the user.
Also from being taken advantage of, as right to repair has shown. If we have right to repair, it's harder for companies to engage in monopolistic practices. Open source does the same thing for software.
> Why would that lead to less open source since companies keeping their software secret, closed source and copyright protected was exactly what lead to open source in the first place?
Because right now, if a company uses open source code in their code, then they will sometimes contribute back to the original software. Without copyright, they won't because their change might reveal something about their file format or something like that.
It's because of copyright that companies have played somewhat nice when using FOSS. Without it, there is no incentive to.
From too much freedom I presume? Or what did you mean exactly?
> if copyright wouldn't apply to software anymore, then companies would protect their software by trade secrets instead
As if they didn't do that already? What part of Photoshop is not secret? Or ar least wasn't at some point until people reverse engineered it? Copyright is the last resort. The first and most solid line of defense for commercial software is alwas secrecy, of source code, of file formats, of binaries in case of server side software, of anything they can keep secret.
> leading to less open source
Why would that lead to open source since companies keeping their software secret, closed source and copyright protected was exactly what lead to open source in the first place?