I would call that a pretty weak argument given that Steam does not enforce any kind of exclusivity. It's certainly a content gate, but developers are free to ship their titles on DRM-free platforms like GOG if they want to cover the part of the consumer base that cares about that.Well, one could argue that Steam is not a storefront but a stupid exclusive launcher already, as it gates your access to the games you've bought. But your point still stands. I wouldn't be a fan of advertising a competitive launcher on my launcher as well.
Not so on EGS. It's their way or the highway, which makes it very easy to make the 'stupid exclusive launcher' argument.