OPB reported two businesses, a truck dealer and and a grain dealer that will cease to exist at least in their current corporate structures because neither nets a 2.5 percent profit now.  Economists who support the measure understand their will be collateral damage but believe that will be offset by the additional money creating government jobs. 
Even if all your points are true this measure has a number of unkowns and the largest unintended consequence I believe will be the actual tax avoidance both consumers as well as businesses employ. An instant 2.5% Amazon price advantage for starters 
I once worked for a national distributor that has closed all but one Oregon warehouse. Likely all sales shipped to Oregon customers will be subject to the tax even if they shipped directly from a Nevada warehouse so lets say that's an additions $2.5M cost the company can easily afford. But look at the incentive they now have to build a new warehouse across the river to save that money.