Well, Partiful is free, available on Android, and doesn’t require an iPhone or iCloud+ subscription to use. In contrast, this seems more exclusive. For now, Partiful lives to fight another day.
RSVPing is clearly accessible to everyone, but how about all the other features? Namely, the "integration with Maps and Weather" and "contribute to Shared Albums". I already know I can only contribute to the "curated event soundtrack" if I have an Apple Music subscription, but those other ones are still unclear.
I created an event and it doesn't seem like anyone can RSVP unless they have an Apple account. They can easily create one but still, that's one more step.