That's a big problem though. They're targeting a class of use cases currently covered by iCalendar family of open protocols[0] and handled by every calendar and e-mail app there is. Because of their narrowed focus on features most relevant to individuals, families and groups of friends, they'll be able to deliver a superior experience there for people on their platform - and they have both enough users and the correct placement in the "tech stack" (unlike e.g. Facebook/Meta or other social platforms, that already tried and failed to pull it off) to break universality of iCal for everyone else.

If this sticks, it won't only screw you or me over as Android users with Apple users in our friends groups. This will quickly bubble up from friend gatherings to community groups and local services businesses. At some point, you'll find that your kids' kindergarten or your stylist or even your doctor starts sending you Apple Invites instead of e-mail invites (.ics), because the Apple variant also comes with a shared photo album. It's actually surprising when you notice just how many appointments could use a shared photo and/or document collection directly linked to them - that part is actually a good idea from Apple. It's just sad that they're weaponizing it instead of improving what already works for everyone.

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[0] - https://icalendar.org/RFC-Specifications/all/