Why a statement by the banking authority might make Germany the crypto valley

Indeed this seems to be the question. I think the ECU (precursor of the Euro) was a defined as a "unit of account" as well. Wonder which definition applies in this case.

Are units of account, and might fall in further categories:

> Based on the specific formulation of the contract for each ICO, BaFin decides on a case-by-case basis whether the offeror is required to obtain authorisation pursuant to the German Banking Act (Kreditwesengesetz – KWG), Investment Code (Kapitalanlagegesetzbuch – KAGB), Payment Services Supervision Act (Zahlungsdiensteaufsichtsgesetz – ZAG) or Insurance Supervision Act (Versicherungsaufsichtsgesetz – VAG) and whether they must fulfil prospectus requirements.

So your ICO might require further paperwork if it looks to much like an investment vehicle, an insurance policy, ...

Looking at the German text in comparison "unit of account" is translated from Rechnungseinheiten. Those are a type of financial instrument that contains private or artifical currencies and are treated similarly to holdings of foreign money. Offering them to the public or commercial trade in them requires permission (as the article already notes).