Timing first, friction later: Whatsapp was first, it extended like wildfire in Latin America before the 2014 buy in by Meta. I attribute it to the ease of configuration: you didn't need an email, it was just your phone number, and then all your contacts were reachable. It didn't lose traction even when it changed from free app to "free for a year". Friction came later, Telegram gained some ground but it was very niche, my friends that were in CS were using it "for the bots and the stickers" but you needed to invite your contacts to use it and it didn't make sense if they already had Whatsapp. Later, more and more businesses started using Whatsapp to chat with customers and eventually it became the default.