Well it died for like 10 minutes, not too big of a deal.
A lot of games do steam only distribution because it is easier and great for marketing. But on the case of goi it wouldn't be possible to not use steam because they use steam services for voice chat. The effort to separate voice chat from steam, just for rare and meaningless cases like those 10 minutes is a large investment of time and money(especially with a small team like Muse.) that could go towards better places.