Yes and WhatsApp is not as popular in the US, with messaging being very fragmented between a variety of other Facebook products.
Then, WhatsApp came and it was free and cross platform, compressed images and video to send them quick with decent quality, and free of spam. Absolutely perfect execution, in my opinion. If it was not owned by Facebook, I’d probably pay a considerable amount for it if it promised security and privacy.
There were no usernames with watsapp, its just your phone number, its so easy that even my mom can use it.