Let's say you have some source code you are releasing under GNU. In this source code contains plenty of nicely named functions, source comments, and even explanations and descriptions of what the code does.
Before zipping up the source code and releasing it.. you decide to go into the source code and delete all comments.. and rename some functions into terser odd looking names. You also format the source code so it isn't as easy to read.
Then you sell a book that describes the source code and algorithms.. based on your old source comments and such. In the book you offer better source code - considering that source to a program is NOT just the cryptic code alone! You then con people into buying your book by simply informing your software users are to refer to your book if they need help with regards to the program or the sources.
This is simply a GNU loop hole... you can charge people for speech. Charging for your book or charging for the commented code, or charging for documentation.. is simply a restriction. Likewise, pointing people to some FTP link where the source code exists without providing them any build instructions or without providing them any pre compiled binaries (which many GNU projects do) is also a form of restriction. 99.9 percent of software users want good documentation and a good working system. Most of them don't care about sources.. so restricting the binaries and restricting the documentation, or restricting people from seeing your paperback book is no longer free software in an ideal world. Indirectly, you are restricting and closing the software in some form or another.
In fact source code being free in many cases got nothing to do with the freedom that 99 percent of users want. For example, if Microsoft Windows source code is released.. do you think 99 percent of Windows users would care? No. Their freedom is clicking the start menu button and seeing it work freely.. even if they paid for the software code itself.
But, I still think that even though GNU is a scam.. it can still bring total cost of ownership of software down and it is still less of a scam than some proprietary crap such as one recent software license I saw where the company does not permit you to own any of the software.. you must rent it.
Do you care about the Molecules in a Banana? Do you care about the construction of those molecules? The typical person wants a banana or apple that he can eat.. and in rare cases he may want to know about the molecules. It is handy to be able to see the molecules in these rare cases.. but in 99 percent of cases we just want to eat the banana. Hopefully the banana doesn't charge us money when we want to talk to it and ask it questions... which many GNU people do. This, is a form of restriction.. and the banana is not free even if released under GNU.
The banana should also not require that I peel it and cut it up.. that is restricting me. It should provide me with a bowl and it should cut up and prepare itself for me.. because in a true free world the banana would provide me with free banana peices, not some restricted banana in a peel that isn't cut up already. The banana is on the ftp server without precompiled binaries!