This is NOT a complaint about the GPL, or any other license. An author of a work is free to choose whatever license they want to offer their work under, including a closed source license. Merely an observation.
IMO . . . when someone offers a Library, that is, a black box of code with well defined API that offers some useful capability, and offers it under the GPL, the author is deliberately trying to RESTRICT what the users of that library can do with their own code. The author is effectively saying that I only want authors of other GPL applications to use my library. If the library author were only trying to protect the freedom of his library and nothing more, then he would have used the LGPL. The LGPL protects the freedom of the library, as well as protects the freedom of the user of a closed source application to be able to re-link the application against a newer version of the library without access to the source code of the application.
I'm not saying this is right, or wrong, or anything else. It is merely an observation.
A library author that offers a library under GPL license has an ulterior motive. Usually a commercial motive to ensure they can make money from users of applications that are not under the GPL. This seems to be exactly the opposite of what the GPL was intended to do in spirit. A library offered under the GPL typically offers a "Commercial License" for applications that are not under the GPL.