Exactly. But since NetFlix and Valve are really the odd man out in the bunch, the powers that be will have their own stores/streaming services up. It's just not how the real life works, having everything under one roof.
And its a good thing too, because then they'd have an monopoly.
And they will always will be if others will not make their alternative open platform, which they will never do ofc. Valve does not see other game developers/publishers as competitors but partners, something Microsoft, Ubisoft or any other big publisher would never allowed.
15 years ago games did not needed any clients and worked just fine, noone is forcing those publishers to use clients except their own greed, they can perfectly release their games as DRM free games as GoG does.