I'm not against open source. However, if I were to guess, I think less than 1% of people actually review, let alone modify the open source projects they use. I don't really buy this argument.
I think we're seeing a new modality of openness now with open weights, or being able to modify agents with md files, skills, and so forth.
I think it's pretty common in software companies to maintain own custom fork of an open-source tool/library.
Before LLMs the barrier to modifying software was much higher - in skill and time investment required.
Now we're getting to the point where any user can say "Claude, I don't like that. Please fix" and have it fixed. Configurability/extensibility can work in some cases, but having source code makes it much more powerful.