Well, the problem is the word "may" which is non-committal and effectively leaves the matter to editors' discretion so that a consensus has to be reached. I'm sorry, I don't understand the term "flagcruft". The relevance is that the teams were multi-national and, in most team sports where international matches take place (e.g., football, cricket, rugby, etc.) the nationality of an individual player is deemed noteworthy. For example, why do Liverpool fans nowadays display the Uruguay flag at matches? Nationality is relevant and flagicons are simply a graphic means of conveying the information.