Why is the city of publication important in most bibliography format? Most bibliography formats require the city of publication for books. Why? In this digital era, ISBN would be way more important. But even before the digitalization of everything, why was the city of publication important?

I can imagine some purposes: 


to distinguish potential same names of different publishers, and
to help book-seekers find the publisher and the book by actually visiting the city or contacting libraries in the city. 


I want to know better stories about the 'city of publication'.
Mentioning the city in the bibliography is important because sometimes the same edition published in different cities would have different pagination, and occasionally even redacted content. Therefore when someone wants to look up the original source, they need to have this additional information available to them.

Another important reason to keep the bibliographic information on place of publication is for reasons of style. Many of us might have bibliographies stretching a century or more, and it would look odd to mention place for some and not for others. 

But naturally changes in citation styles are continual, and another element of the citation that is of lessening importance is the page number for journal articles. For one of my publications, I was actually required to remove the page numbers in the in text citation, because the relevant information is easier to find using a search engine rather than by leafing to the correct page in a printed copy.