I think that, besides the pressure to release new material, a subscription system can be a nice thing for lesser-known artists. Death Dynamic Shroud seem to do very well with their exclusive mixtape club thing ! (in France, we also had a big name of cheesy pop music who launched his own streaming platform a few years ago, he releases exclusive stuff on it, perform private concerts etc. - zero interest to me but if you're a big fan I imagine it's something very worthy)
It also depends a lot on the amont of money you ask from your fans. If I were to pay 2 or 3€ / month to support an artist I love, I would understand that there wouldn't be something new to listen to every month.