> So basically what we have today is exactly what the market wanted.
If "the market" means "companies" then yes. "Users", not so much.
Much like Apple getting rid of Flash, if MS had a dominant market position they could have forced a user-friendly trend. Alas.
Users didn't care either, companies used the opportunity.
When it was pointed to them, what they could have ("all the instant messaging in a single app"), the answer was a blank stare and a reply, why would they want that, they are perfectly fine launching separate apps.
The plugins never materialized. Every third party wanted complete control over it's app, which later developed into stores for digital goods, wallets, etc.
The situation was not helped by the fact, that there was no such system on iOS and the only way for a messenger to wait for messages on the background were push notifications from Apple servers. Here people expected separate apps for separate chat networks.
So basically what we have today is exactly what the market wanted.