It does smell a bit funny, but in a way what they do is not just copy an app but rather create an international / European knock-off. They identified a weakness

It does smell a bit funny, but in a way what they do is not just copy an app but rather create an international / European knock-off. They identified a weakness in the way American startups operate - concentrating on the American and/or English-speaking market for very long while neglecting the rest of the world, and they're taking advantage of that. Their business model would become obsolete if startups became better at addressing international markets.