I've recently reviewed manuscripts for two interdisciplinary journals, journals in which philosophers can and do publish but in which articles by philosophers would be in the minority. I later surmised that the manuscripts I reviewed were not written by philosophers. Both had features that struck me as being unorthodox. Most notably, both manuscripts contained many references to the authors' extant published work. They also included long (200 word+) quotations from the authors' previously published work, flagged such (e.g., "As I remarked in my (2005)…")
So far as I know, this sort of self-plagiarism would be unusual in a philosophy manuscript. Anonymous references in a philosophy manuscript are common (though one objection to them is that they essentially blow the cover on blind review), and it would not be strange to have many such references if the manuscript were part of a symposium, etc., where the author might say things like, "In response to this criticism about X, let us revisit my article on X." But I found this strong reliance on the author's previous work off putting and unprofessional. It seems faintly like a fallacious appeal to authority, for one. What if the position, arguments, etc., of the published work being self-plagiarized weren't convincing in the first place? And if all the arguments were made elsewhere, why should the manuscript I'm reviewing be published?
Lastly, it looks like a way to pad your CV: republish, with small modifications,what you already published. This seems unfair to those authors who have actual new ideas to contribute.
Yet I'm also willing to concede that my reaction may reflect norms about originality, authorship, etc. specific to philosophy. So I'd be curious to know if others have reviewed manuscripts with these features; if the practices I've described are common outside philosophy; and if self-plagiarism (taken to this degree at least) is unprofessional.