Everyone used to have only 1 email address. Nowadays, most people have multiple email addresses for different use cases (work, spam, personal). I think this will be the norm for messaging apps as well.

Isn't this already normal?

How is the inherently bad? With most people having phones as powerful as computers, there aren't any technical limitations to this.

My phone may be able to handle running a thousand messaging apps at once, but my brain can handle at most one or two before it melts from the sheer ridiculousness of having to deal with the different user interfaces, privacy policies, compatibility issues, etc. of a zillion companies just for something so bizarrely simple as sending a message to a friend.

Yeh I think having 5 messaging apps on your phone is fairly normal already.

If you have only five you are already lucky.