how important are the roots for the size of your plant?

just wondering how important the roots are for determining how big your plant gets. i was thinking what would happen if you filled up a big rubbermaid container up with soil and then just grew the plant like you normally would. would a bigger area for the roots to grow make a difference in how the plant grows?

a marijuana plant is alot like a tree especialy when it comes to roots. with trees the root systems can be as big as the branches above ground. the same goes for marijuana plants, the bigger the roots, the bigger the plant. but it is possable to grow some berty big plants with small pots. you just have to take extra good care of them and water them alot.