Valve announced a replacement feature for both Family Sharing and Family View. Currently in beta.
Features:
- up to 5 members
- game sharing
- parental controls
- allow access to appropriate games
- restrict access to the Steam Store, Community or Friends Chat
- set playtime limits (hourly/daily)
- view playtime reports
- approve or deny requests from child accounts for additional playtime or feature access (temporary or permanent)
- recover a child’s account if they lost their password
- child purchase requests
This specifically says that getting banned on a shared account will also ban the owner who shared the game. Likely to prevent exactly what you described, where people could evade bans simply by sharing their library with a throwaway account.