Huh? Sharing an Apple ID between trusted household members means purchased apps can be shared between members. And since each user can have different Apple ID for personal data like backup, documents, photos, calendars, reminders, and email, you get best of the both worlds.
Exactly. My wife and I use my AppleID for all app store purchases. She has a separate I'd she uses for her contacts, calendar and email. Works great. And I use my ID for my email and all that stuff. Works great with no issues.