And so you can actually learn to play poker. I think playing with a short stack really hurts your growth as a player. After youve learnt which hands to go allin with preflop and which ones to fold you cant learn anymore. Reads dont help you because once the flop comes down you are out of chips to make any more descisions.

In poker you make money by making correct descisions and by making opponents make incorrect descisions. Each chip is a descision waiting to be made. If you play with a tiny stack you arent having to make any postflop descisions which means you arent going to be able to take advantage of your opponents horrible postflop play. It also means you won't ever get any better at making these descisions.
If you start out with the assumption that you are a losing player you need to study/ move down in limits until you are winning.
If on the other hand you are a winning player then you will win much more with a bigger stack when worse opponents pay you off.

edit: I don't think it is necessary to play with a completely full stack but i certainly wouldnt get any lower than half a stack. At 25NL i would play with the max. buyin (if i could afford it) because the max buyin is only about 100BB. I play 5NL at pokerstars and the blinds there are only $0.01/$0.02 so buying in with $2 would be 100BB. Ill usually buy in for $5, sometimes $4 and very occasionaly $3 but i wont go below $3 because i think i have a big enough skill advantage over the other players to let myself play some real poker postflop.