This is a good question - I disagree with the conclusion but I think that it is worth discussing.
In the question mentioned, what was asked hinged heavily on cultural norms. How to negotiate a salary is something where there is still a great deal of discrepancy in how it's handled.
However - there are other Workplace issues that are less influenced by Culture and more to do with Law and Regulation - as such, the EU and ECJ (European Union and European Court of Justice) are most likely applicable. Even non EU countries, such as the UK (heh) have a fair degree of overlap in terms of Workers rights and protections.
As such, a Europe tag is appropriate IMO when used in the correct context.
I'm not familiar enough with Asia to give an equivalent answer - but I suspect that there are indeed some cross-overs in the Asian region (especially those that share a landmass - such as South East Asia) that such a tag, when used in the right context is applicable.
In a more broader sense, most of what is asked here is applicable to Corporate life - which for the most parts means it's heavily focused on the USA, Europe and Asia. And since everyone knows that on the internet the default is the USA (I jest...) - then having the tags to essentially say 'Not the USA' has merit.
I do, however, agree that having country tags is perhaps something that should be considered. The only pause I have for saying this is that restricting people to use Country tags may inhibit a user from asking a question, especially if it's a niche field or question and disclosing a country could make it identifiable.