Ctein is a very clever fellow and anyone who reads his books and articles will know how scientific his analysis is. He is essentially looking at the fine margins of printing which, as with all worthwhile study in detail, has a broader implication and comes with useful insight: delving into the real nitty-gritty of what occurs in a process, for example. Ultimately, it is what creates further development and he had responses from paper and lens manufacturers on this issue (and they concurred that there is a focus factor), which is no mean feat. Furthermore, the possible solution creates another set of theoretical problems: as with most things compromise is the result, but at no great cost to ourselves, quite the reverse.
Personally, I can live with the fact that I am not going to achieve 'perfect' pictures, but I am grateful that others are looking into this and giving me the benefit and, maybe, helping to keep alive the advancement of our silver world. (It's what the good forums, like this one, thrive on and perpetuate).
Thanks, Mark Walker.