i reckon steam is lacking on this because steams basically the only client that natively has a steam client on all platforms officially. it doesnt see it as a problem because of that.

Microsoft needs to make it so i never need to go into the steam app or the GOG app

That's never going to happen with any store. Not Microsoft, not Steam, not Epic, not GOG. GOG games could be added anywhere, since they're not tied to a launcher.

Either start pirating everything or "hope" one store on PC gets a real monopoly, so it's the only one to buy from.

I think Microsoft is too big to make sensible and timely changes. The company needs to be broken up. Windows, Office, Azure, Xbox, Bing, all need to be separate companies with their individual sustainable business plans, or else let free market decide their fate. Same for Apple and Google.

I am surprised that steam is even lacking on this.

This is an „underdog” feature - if you own the market like Steam does it could only ever harm sales on their platform. Some people don’t seem to be bothered by the grip Valve has on the market however. Not like Microsoft wouldn’t do that either if they were in the same position because both are ultimately out there to make as much money as possible.