📝Software is not additive
Software is not additive—it deteriorates over time and becomes obsolete together with ideas that were used to create the software. Unless those ideas are fought for in an additive medium (e.g., books, posts, etc).
Counterarguments
If source code is available, it can be studied, and ideas can be extracted.
Reverse-engineering.
The main downside of the two counter-arguments above is that they require much additional effort. It’s much harder to extract ideas from a source code or binary than from a book or article. Some higher-level / design ideas may not get represented in the code (or get distorted), so they are impossible to extract.