It would be useful for separate sale sections.
I like neo-geo.com but don't use the sale section as it has sellers from everywhere but mainly from USA. I don't like importing games if I can help it as I don't like paying high shipping costs and also custom charges.
Separate sale sections would make it easier to avoid foreign sales if you don't like paying the extra costs on top of the selling price.
There are lots of foreign collectors but most probably stay to their own country forums so that they can discuss/talk about their collections and participate in resto's, general chat etc
Generally on here there are less than a handful of expensive foreign sellers that have several accounts, bump like crazy, over price all their "collections" and are here to avoid ebay fees. I just avoid looking at their "collections" now and move on.
I have previously tarnished all foreign sellers with the same brush unfairly due to being annoyed, but most of my collection is from foreign sellers that were not greedy and were great to deal with