well, you do not need to do it on your main account. you could set up a new account and just use that to post your invoices. That way you do not really "rape" the reward pool and there are no votes to lose. But you are being provided with an eternal free storage method. nobody would notice it, there would be no followers hence also none to lose
This is a solution that could work for a while of course but if everyone and their dog started saving every paper on the blockchain on dummy accounts then this would potentially change the whole purpose of the chain (personally I think its to late for that but it might have been a possibility)
What if? can be a cool question sometimes