Clearly if a person is good enough to play for their county they need to be registered with the correct federation in their FIDE record, does it makes any difference to other chess players?
does it makes any difference to other chess players?
Only in very special circumstances for special players. Only if a player is trying to get a title norm (WIM, IM, WGM, GM) in a tournament which qualifies as a norm event does the FIDE federation of the player's opponents matter.
According to FIDE Title Regulations effective from 1 January 2022:
1.4.2 The following are not included:
Games against opponents who do not belong to FIDE federations. Players with federation “FID” are accepted, but do not count as a foreign player.
... 1.4.3 Federations of opponents
At least two federations other than that of the title applicant must be included, except 1.4.3a - 1.4.3d shall be exempt. Nevertheless, 1.43e shall apply.
So, if you are playing in a norm event then for your result to qualify as a norm then you must against players from at least two other federations and FID does not qualify as a different federation.
In all other circumstances the federation of the players (as long as they have a federation) is irrelevant from a chess perspective.