Honestly, I wish they'd enforce the "require no account" rule more strictly. One of the most annoying things about using a mobile app is when they hit you with the "Sign in or GTFO" page on first run, as soon as you install the app.

At the very least, if an application absolutely requires an account to function, this should be prominently displayed, and they should explain in technical details what functionality cannot be possibly achieved without logging in. App Stores should reject apps that gate basic phone functionality (like GPS directions or camera access) behind an online account. These things obviously don't require an account to work, because they work on the default apps without accounts.