Surely before the selections you would check if a player will be inactive or not? The reason for having 3 changes unlike the NWEC that had none is so that if out of the blue someone has to go or do something then you are able to swap him out.
Inactive as in not participating in the matches.
You can't tell whether or not someone will join before they've actually had a chance to join, but by then it's a bit too late.
How detrimental would it be if teams were allowed limitless swapping? It's not like half a team would be changed if it's already active and able to field a great number of players.
I'm concerned for the mid-sized teams that may not have that many to choose from anyway, like Denmark. I can easily find 20-something interested, but also potential inactive players, and granted the roster is capped at 14, I don't really have any options left, even if I have a couple of danish friends online when I need them.