This statement is wrong on many levels. I'll try to correct just one part:
Your buoyancy must NOT decrease as you go deeper. That's one of the fundamental rules you need to follow if you want to dive more than once :) If you don't watch your depth and take necessary steps to maintain neutral buoyancy, you'd sink like a stone (or rise like a balloon). Nobody wants that.
What you mean is: you need more air in you buoyancy compensator (BC) to maintain neutral buoyancy (= keep your volume constant) as you go deeper.
If you don't take weights, you need to inflate your bc to lift you. In an emergency, you generally don't have time to swim up anyway.
All that said, I was just trying to point out that it was possible to "fall home" from underwater, assuming you are within the limits of your equipment.