ChrisTX: I suppose unless one is absolutely disgusted by Steam, you'll end up with an account there sooner or later. That's the problem basically; most AAA titles and a lot of indie titles are sadly not available as DRM-free.
Because of that, keep in mind that Steam will remain the most important digital distribution platform for the foreseeable future and games developers will always care for their Steam customers first.

In this specific case, the developer uploaded - according to their tweets - first to Steam and then to GOG. Now, I don't know how GOG packages the uploaded files/patches, but maybe it indeed has to be done manually by a staff member of theirs. Certainly, that's not as flexible as Steam's content depot system - but that's always the case for installer-based distribution. (I'd also like pointing out that the only "Steam feature" this game supports is trading cards...)

Either way, yes, Steam has its perks and binds its customers. I suppose the most dangerous part is the Steam Workshop in this regard: Workshop games have almost no mods available outside of the workshop, thus putting DRM-free customers in a bad position. In general, the more developers embrace Steam, the more users are bound to it. This in turn permits Valve to put up pretty customer-unfriendly EULAs and the users have to abide to them if they want to play most PC games. A single transaction charged back or PayPal charged back because of a lack of fund on the specified payment source? => Account disabled. Same holds for proxy usage, where it's unclear when that is permitted and when it isn't.

Even if you're not a DRM-free purist, you should consider Steam's near-monopoly and rethink whether you want to unconditionally support that, just because some patches arrive here later than on Steam.