That's a special case. The sheer volume of beer that it requires to give you alcohol poisoning is often larger than your stomach. If you're drinking a "lite" beer, you're drinking slightly piss-flavored water.

There are no volume issues with pot. You can smoke an enormous amount of weak pot or a tiny amount of strong pot, and it will take up exactly the same amount of space in your lungs: none, unless you forget to exhale.