It's true, though. iMessage requires an Apple device, and Apple simply doesn't have a lot of market share in Europe (around 30% for iOS, less for macOS). So most people don't have access to iMessage.
Yeah that's what I meant, they don't have the critical mass to really put it on the map here. It falls back to SMS for Android recipients of course, but group chats and pictures/video are out of the question.
So in practice nobody in my circle uses it whereas Whatsapp is huge (still). I don't have iOS but I would notice if I got SMSes. The only ones I still get are insecure 2FA and spam.