Well it's matter of comparing it to their competitors. GOG actively advertises and encourages devs to eschew DRM, lots of games became DRM-free just to appear on the store. Humble also actively advertised DRM-free games, and even source-available games, though granted, nowadays it's more of alternative steam store interface with charity, with very few direct download titles. itch.io, due to the area they operate in -- niche indies -- it's pretty much cultural standard to have no DRM, so they don't even have to mention it.

I don't like stores that proliferate DRM. GOG has the right approach about it. They simply don't allow DRMed games in their store and actively work with publishers to dispel their messed up DRM mentality.