That is one thing I absolutely hate. I placed a large order the other day, they agreed, and took my money. Said they shipped 80 out of 480, the rest would ship “at another time”. I was heated, absolutely heated, it was a very significant amount of money and they told me it was on hand and ready to ship. Well it cost them several emails and a phone call. I think I have established with the owner that is shady and they made it right in the end.
Selling things you do not have on hand is a fragile way to do business. I could imagine doing preorders for something but that would be a limited run for sure and it would be very clear to all involved. I guess more of a group buy than a preorder I suppose.