They are doing the same thing on the CW, putting Swamp Thing on the fall schedule, which was specifically made for the DC Universe streaming service. This is mostly due to production delays and shutdowns of their regularly-scheduled shows, due to the coronavirus crisis. They had to fill in the fall schedule with something, so it may as well be something that they already had in the can, that has never aired on broadcast TV before. If / when production of the regular shows gets back to "normal" then things will go back to business-as-usual for the shows that are normally only available by streaming.