I can understand why you were modded down (boo Quickbooks) but for a lot of small business owners it's a tempting strategy. And with people out there pushing carts that integrate with QB 'out of the box', it makes building something custom for people a harder sell.
What boo Quickbooks? It's what people use. It's a bit rich expecting businesses to switch bookkeeping software (which their accountant/bookkeeper recommended & uses) because your cart has a better idea.