Compulsory to whom or in what sense?
If you refer to being successful online than no. It's not even necessarily advisable. Their are many more effective and free ways to advertise over the long haul.
Now adsense may be a different story. I can definitely see the advantage there if used correctly.
At Wealth Creations Network we help people take their passion and turn it into a continuing revenue stream. All at zero out-of-pocket cost. Drop me a line or visit my webpage via my profile.