This is patently false. Most alternatives to GNU software are permissively licensed (MIT, BSD, Apache, etc.). Just look at musl, clang, bzip2, and the various “new” userland replacements like ripgrep, neovim, bat, exa, dust, etc. The one notable exception is busybox which is GPL 2.

I don’t know why this trend exists, but I am constantly disappointed that talented young open source devs choose to sacrifice software freedom just because it will make their software easier to integrate in proprietary contexts. This strikes me as pure vanity or greed on the devs part so that their software is more popular and maybe even monetizable.

I hope that trend halts, but time will tell.