I don't know how it is over there in Europe, but here in the US a lot of people are traveling in the week before Christmas, to be with family on Christmas Eve and Day. So this FA ending on the afternoon of the 21st here in the US will definitely conflict with the travel plans of some players. I would not be surprised if Inno's numbers for this FA show a huge drop off in Pit participation. I know as soon as the three stages are finished, I will not be touching the Pit because I am one of those people traveling for the holiday.
Europe is not as large as the USA, so travelling takes less time. If at all, as most people who have jobs, just go to work.
Most people in European countries celebrate 24th and/or 25th, but the Dutch count 25th and 26th as Chrismas days. This can be slightly different in each country, because of cultural differences.
All other days, before Christmas and between Christmas and New Year are ordinary working days. Except for schools, children have vacations during the last week of December and the first week of January.
As Inno is German, I can imagine that they have taken Europe as a reference here, not the USA.