Someone else on mastodon found this https://masto.ai/@stavvers/112655306069874958
EDIT: they might actually be the original author of that? I can’t find this indexed anywhere else online (google, google scholar, and google books all turn up nothing or just that mastodon post)
Not necessarily. Self citation is different than building on your previous work. You might just seek to use other citations for the relevent concepts
Edit: the 2015 paper this is referencing lists many differing potential reasons for it. Ranging from worrying more about negative feedback for self citation to being more likely to being more critical of their own work
https://journals.sagepub.com/doi/10.1177/2378023117738903