Steam is not a subscription service

Steam provides a cloud service. Not dissimilar to other subscription-based services. Had they been using AWS, they would also have been affected by the outage, resulting in Steam also being mentioned in the headline. So it's just as relevant as the others.

you'll never own a piece of software by buying it in a video game store.

Sure, I'm both granted a license on both Steam or GOG, but the crucial difference is still about offline access. If GOG stopped existing tomorrow, I'd still be able to install, and play, all my GOG games. The same cannot be said for Steam. Which one, then, grants the most ownership? License or no license.