When exactly was this?
That time when they offered free games to people that owned the Steam version. That time when they made a hilarously infunctional client/launcher. That time they introduced "achievements" and assorted other cereal box backside level customer loyalty schemes like Valve does. That time they started to hide the exe installers in your account and started to call those "backup installers" like those are not really why you bought the game here. That time they introduced "player profiles", never created a functional opt-out option, and sent their community into a flat out riot. That time they created their version of Steam Early Access so they could sell unfinished shit too. And right now they're desperately trying to create a program that lets developers automatically make a bad port of their Steam game to sell it on gog.
The list goes on.
GOG didn't really "make a play for Steam market share". They simply started scraping between Valve's toes.
Sorry, but I don't see any of that as trying to grab some of Steam's market share, just offering gamers who might buy at GOG instead, some of the features they desire.
And honestly, the number of games provided using GOG Connect was quite small, and just one of many promotions for the store, as all stores engage in, in one manner or another. And those few games would only appeal to the small group of gamers who care about getting a DRM-Free version, which would not be most gamers by an enormous margin.
GOG is really only an alternative to Steam, for those few who care enough about DRM-Free, or where a game doesn't exist at Steam. For GOG to compete with Steam, they would have to be providing a similar or better option that the majority of gamers would care about, and they never have and I dare say never will.
You have more chance of Veganism challenging Meat Eating in anything like significant numbers.
At best, GOG is a drawcard for those who don't like the Steam model, which going by the percentage of gamers who feel that way is incredibly small. Any profits Steam have lost to GOG over the years is unlikely to make Steam bat an eyelid over.
And in regard to comments by at least one other, GOG need customers, and will indeed at times, match what Steam does if they can, to keep their existing customers, especially as many gamers often care more about price than DRM-Free state. And then Steam often have what I call games that are DRM-Free Lite, which I guess you could call being competitive, but once again sales numbers tell a different story ... no real competition to speak of.