That’s fair, but it is a part of the license. To me, it makes sense that collaborative open source projects are licensed under the GPL: it forbids taking fruit from the community garden for free and selling it for profit.
But for a library project, GPL is quite an unusual choice. I don't know any commonly used library, that has such a restrictive license. Most of them use LGPL, Apache, MIT, BSD or something similar. Otherwise your library is commonly doomed to be a stillbirth.
Ghostscript is one example, a lot of users ran into legal trouble using it.
