A single plant can easily produce 500 grams. In other words - you could be killed for growing one plant for your own personal consumption.
It's certainly very easy to stay under this limit if you're growing at home. It's difficult to cross that threshold accidentally, for sure.
500 grams is roughly a pound. 2 pounds (or more) of trimmed flower per plant is very achievable growing outdoors with many strains (not autoflowers).
(this is actually inconsequential to the point of the article I just wanted to point it out).