It isn't just "the default behavior", it's the only behavior. Owners always have full control on their own objects (including grants and revokes on those objects). That's why separation of container schemas from accounts that login to the database is so key to database security.

Disclaimer The original answer was posted as a comment by @KrisJohnston

Addition

There is a slight twist to the answer in that the permissions can be changed so that the owner can longer modify his own objects, BUT the owner is then no longer the owner. This is a loss of ownership for the original owner.

This can be achieved using the following technique:

How to change an Oracle table owner

create table bill.emp as select * from scott.emp;