I've never seen a number that high in my field, maybe 500 or 600 for the big shots, and even that seems wildly unreasonable to me. Feynman had about 85 peer-reviewed papers over his lifetime, which is less than two per year during his career, which is a very reasonable number.

Authorship and citations are basically academic currency, and as such have undergone inflation just like real currency. Professors get their name on a paper as a form of payment for future or past services to other professors (often related to funding). There's just no incentive for anyone to stop this as far as I can't tell, and appealing to ethical conduct in authorship and citations is not enough.