Yes you can. You do not necessarily need a confirmation if you are willing to take a small risk (and a vendor accepts risks much bigger than that if he's in business).
Bitcoin-type technology has tons of potential, my friend.
The point of the person you're replying to is that, for 99.999999% of businesses, there is no benefit to using BTC. It doesn't offer the buyer any protection, it's extremely volatile, and it would require an overhaul of the entire economy's infrastructure to implement in any meaningful way.