As I said, I think it is okay for authors to make any request they want, it is their software after all.
But I still think making citation for gnu parallel is unreasonable. There is a huge body of software, of which gnu parallel is probably the least important, that contributed to (at least my) research. Blowing up citation lists with those makes the citation list borderline useless.
It makes citations into advertising space for software - it's bad enough being coerced to make it an advertisement for reviewers papers.
But I still think making citation for gnu parallel is unreasonable. There is a huge body of software, of which gnu parallel is probably the least important, that contributed to (at least my) research. Blowing up citation lists with those makes the citation list borderline useless.
It makes citations into advertising space for software - it's bad enough being coerced to make it an advertisement for reviewers papers.