It depends on your perspective. Currency trading is mostly done through the dollar. If a German trader wants to buy Yen and sell his Euros, he will typically buy dollars first and then use them to buy Yen. The Euro/Yen cross is quoted but is not as heavily traded as each currency is against the dollar.
EUR/JPY is one of the major crosses. The volume might not be as high as EUR/USD or USD/JPY, but it is certainly traded regularly in the spot FX market. Why would this "German" pay two spreads when he can do it directly with one spread?
It depends on how wide the two spreads are versus the one and how liquid the market is at executable prices. Figures: It is where the liquidity is at. It's not that that Euro/Yen doesn't trade, it does, that's why I used the qualifier "typically". There would be a lot of factors going into whether you trade it through the dollar or directly.