I work on viral FB apps, it is a numbers game. Without an auth flow the 2nd day retention is maybe 1-2%. With an auth flow + wall posts, it is true that 60-80% won't auth the app, but we get enough people who do and come back the second day to make it very worth it.
Facebook policy is that an app should not autopost without permission, even if technically there is the capability, and that policy is enforced on their end and respected on ours, so you are still free to auth the app but decline the autoposting if you choose to.
Facebook policy is that an app should not autopost without permission, even if technically there is the capability, and that policy is enforced on their end and respected on ours, so you are still free to auth the app but decline the autoposting if you choose to.