There may be other requirements of schedules aimed at ensuring reasonably failure recovery. If T9 is allowed to commit before T8 and if T8 fails after T9 commits then we have to roll back T8. But T9 has read a value created by an aborted transaction and, to ensure atomicity, it should also be rolled back. But, we can't roll back a committed transaction. The schedule is an example of a nonrecoverable schedule which would not be allowed by most database systems.
Most databases require that all schedules be recoverable.
A recoverable schedule may require that many of its transactions be rolled back when one of them fails. But T13 read the value of B written by T11 so T13 must be rolled back. But T12 read the value of C written by T13 so T12 must also be rolled back. This is an example of cascading rollback - where a single transaction failure leads to the rollback of more than just that transaction. Many DBMSs ensure cascadeless schedule because of the great amount of work involved in cascading rollback.