Bitcoin-QT wallet.dat prior to adding passphrase On almost any Bitcoin-QT tutorial I notice people recommending to: 

(step 1) back up your wallet.dat before adding a passphrase.  
(step 2) Add a passphrase and copy your new wallet.dat to a USB .... 
(step 3) Write down on a piece of paper the used passphrase .

Isn't (step 1) problematic? 

Say I copied wallet.dat prior to adding a passphrase and just dumped it somewhere on my computer or god forbid on a USB and the USB gets lost or computer is hacked,  wouldn't an obtained wallet.dat prior to adding a passphrase, will grant access to the new (and thought to be passphrase secured) wallet?
I presume the reason for step 1 is to protect you from losing your Bitcoins in case you later discover that remembering your passphrase is beyond you. If you understand the relative dangers and conclude that not keeping a backdoor around your new passphrase is the right way for you, I suppose you could try skipping step 1.