WebJunkie: At leastl Steam still works! Having never bought from them for over 2 years (which will now change) their steam client just 'works'.
Cavalary: Wouldn't know and wouldn't care about clients (and I guess Galaxy works for browsing GOG too? another thing I wouldn't know or care about), but it's not just Steam. Just did a quick check, just seeing whether anything appears broken, whether I can browse catalog, get to game pages from it or add something to cart, and Steam, Itch, FireFlower, Zoom, Humble, GamersGate, Origin and UPlay all worked (granted, no account on Steam, Zoom, GG, Origin or UPlay and not signed in on FF, but that didn't seem to bother them, only Origin popping up the log in or sign up page, rest being happy to add to cart and sort out login later). GOG doesn't. That should kill any argument that the browser can't be worked with anymore, even when talking specifically of a gaming site, eh?
Only browse Steam occasionally and it's the only client I have installed! As soon as Galaxy is forced down your throat and made mandatory I will ask for my account o be deleted! Wouldn't care about those other sites you go to, and since I won't buy from EA or UBI I won't have to install their garbage clients either! Steam web page works fine too in IE11 so can buy from Steam using web or client, only GOG then seems unable to code a functional website!