You can push your own ecosystem of apps and still allow your customers to replace them. I'm not aware of a Samsung app or service that cannot be swapped out. And I struggle even more to find a Samsung component that is designed to create network effect lock in like iMessage is. And Apple Messages can't be swapped out, it is the only texting app on iOS. You can install Signal or Whatsapp or whatever, but you can only talk to other people who have those apps installed. You cannot use them to talk to any phone number like a texting app can.