If they integrate Steamworks, these games usually (not always, but exceptions are rare) will not start up if Steam isn't running. I am speaking as someone who cares about and tests this.
Ironically, I have actually had far more success with stuff from the Epic Games Store. Lots of major titles such as Beyond Two Souls and Ratchet & Clank: Rift Apart function as completely standalone, DRM-Free binaries once downloaded, it's great.
The effect is the same if it means I can't launch my games without authenticating with a remote service that could go bust at any time, and has already dropped support for legacy operating systems which I still use.
Sure. It's still not DRM, which serves no benefit to the player, unlike network capabilities. The risk of Steam disappearing is lower than the risk of me losing the download code or WoG's download servers disappearing, so Steam is the better bet for me.