The having to do something is the cost, because they have a perfectly good messaging app already, "why can't you just use that?"
And that cost is more on Apple's platform because Apple has been designing it that way since the beginning. It's the whole reason android users got a different color bubble, not because they had to, but it was a way to identify the person that wasn't using an iPhone and make them stand out. Making it almost unimaginable to switch to Android for youth who care so much about not being "out" of the group.
And Google has identified this, and put a lot of cringe-worthy effort into addressing it at their Pixel event this time around.