It's not necessarily dishonest so much as it is difficult. As Jheartless mentioned there are a lot of variables that can affect just how much fuel income OKW is receiving including map size, fuel conversion, and salvage. OKW never receives less than 66% fuel income (unless converting it to munitions) but depending on those variables their actual fuel income can fluctuate wildly.
The issue is converting robs of you of valuable resources early game which is a killer as you need to get Shreks out ASAP will maintain fuel income to tech up. Yeah if you luck out and get a lot of salvage you will be able to get ahead, but that also probably means you enemy is playing quite poorly so it's probably a win anyway!
The fact is that you can rely on purely mp to stay alive and that is a department on which OKW is cost effective.
Sure you can rely on it to say alive theoretically, but your shreks and Obers won't do jack shit to howitzers and other forms of indirect, which will quickly force you to give ground.