何のためのバリデーション？

窓口で列に並んで無駄な時間を費やすのを防ぐためのものなので、このものを持って窓口に行くのではバリデーションの意味がなくなります。連続性型はオンライン購入し自宅プリントができるので、それで買えば混乱もなかった筈なのですが・・・。一般論ですが、説明書って、個別に細かいことは書かずに、色々なケースをまとめてかくので、なかには不要なものまで書かれてしまうことが多いのです。まあ、法律もしかりで、紛らわしいとか現実にそぐわない、想定外のことが発生したさいには修正する作業が必要なわけで、絶対的なものなんて存在しないと思えば、後は論理的に対処すれば解決できるのです。

If the pass is issued “open date”, the passenger chooses the first and last day of travel and this must be inserted by the Issuing Office or by a DB Ticket Office before the passenger starts with the first trip. A ticket inspector may also validate the Pass when the holder arrives in Germany on a train from abroad. The passenger must not fill in the validity dates him/herself.
この作業はopen dateのみの場合で、すでにvalidatedなので、必要なし。

ここも単なる販売会社ですが、
www.germanrailpasses.com
How do I activate the pass?

Your German Rail Pass must be activated before you start using it. This must be done within 11 months of the issuing date. German Rail Passes must be activated by a railway official, who will enter the first and last day of validity on the pass.

You can go to a DB ticket office to have your pass validated before you board your first train. If you arrive in Germany on a train from abroad, a ticket inspector on the train can also validate your pass.You cannot enter the first and last day of validity on your pass yourself.

この部分が代行されているので、窓口に行く必要はないのです。

forum.raileurope-world.com
German Rail Pass need any activation before use ?
Passes must be validated within 6 months of issuing date by a railway official in one of the countries mentioned on the rail pass (station’s desk) who also fills in the passport number.

Passes must be validated prior to boarding 1st train (All parties must be present when validating a Saver pass).

The date of travel has to be entered in the correct way before boarding the first train, by the traveler, in the corresponding box of the calendar.

この手続きがすでに済んでいるので、やはりこれ以上することはありません。