Even though "... anyone can RSVP, regardless of whether they have an Apple Account or Apple device" I think this being an Apple branded service is going to make this appear exclusionary and will mean some people won't participate even if they could.
I see the same risk involved with Apple TV's branding; Apple TV works great on Xbox, on NVIDIA Shield and on PC. I'm sure though there are a lot of people who just decide that shows like Foundation and subscriptions like MLS Season's Pass just aren't for them. I don't know if it is a 5% or a 20% drop but it has to be real.
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