There are two powerful arguments in favour. In countries where there isn't a national rating system, it substitutes for one. Where there is chess tourism, it facilitates this by facilitating cross-border play.Richard Bates wrote: Interestingly there are some people, (or maybe more accurately one fairly influential person?) who seem to believe that FIDE rating virtually all chess is some sort of Holy Grail.
What you have to allow for is the disincentive effect of rules and regulations. In 1972, the BCF had a registration scheme, if not a licensing scheme, Congresses were outside the system but still able to be graded. This meant that organisers could establish British Congresses with entrants exceeding a thousand players without the national chess body saying "no" or "not permitted". Actually they probably did try to say that, but were overtaken by events.
It may well not even be legal for the ECF to collect passport information, but such a process would be more likely to be accepted if international ratings extended no lower than 2000 or even 2200.