Not being an asshole? It's normal instinct unless one's brain has been thoroughly eaten by competitiveness.
> Why is that bad?
Because in this, Apple is attacking the commons. They're trying to provide an alternative to normal invite system - one that's been established and battle-tested over decades, one that works okay-ish across any device, real or virtual, on any platform, and one that people know how to use. An alternative that gives some bells and whistles exclusively to the Apple users, and perhaps even is more ergonomic in practice. An alternative that overlaps with the commons just enough to perhaps get the significant chunk of Apple-first userbase to switch over, but purposefully doesn't overlap enough to work well for non-Apple users (as well as professional users).
Take commons, drive a wedge down the side, use it as lever for your massive userbase to push everyone else off it. Screw everyone else. Hell, even screw your own users too for having Android users (or Windows or Linux desktop users!) among family and friends. The next generation of users should remember that thou shalt only befriend and marry people from within your corporate community.