I’m not sure why these comments are so negative so far. If I’m understanding the article correctly, it is an optional setting to automatically open the app as soon as it is done installing. The Play Store isn’t just installing and opening apps on its own.
I’m from the US as well, and I can verify that very few average people use those types of messengers primarily. It is almost exclusively iMessage and SMS/MMS/RCS texts as the main form of messaging. I will admit that quite a few people will use the messaging features that are built into social media apps (like messaging in Snapchat, Facebook Messenger, etc). At least to me, it seems like those are moreso used for sending memes or messaging people you don’t interact with regularly and are still secondary to the other forms of messaging.