Many apps have network effects. You can put together a great messaging app but if Apple bans it or cripples it, it can't catch on.
And that's just as true while you're small. You have six friends and three of them have iPhones, you can't get them all to switch to your own app.
Meanwhile Apple's "loss" is of an app that they purposely didn't want, e.g. because it might have displaced iMessage by being a better SMS app (which they don't allow). They don't ban everything, they ban the things that are in their anti-competitive business advantage to ban.
And that's just as true while you're small. You have six friends and three of them have iPhones, you can't get them all to switch to your own app.
Meanwhile Apple's "loss" is of an app that they purposely didn't want, e.g. because it might have displaced iMessage by being a better SMS app (which they don't allow). They don't ban everything, they ban the things that are in their anti-competitive business advantage to ban.