Except this actually ensure that no client will be pissed off because he confirmed his purchase only to discover that price dropped 1 min after... By interrupt

Except this actually ensure that no client will be pissed off because he confirmed his purchase only to discover that price dropped 1 min after... By interrupting current carts and letting customers wait a few moments it help easing out this kind of bad surprise. And by the time store get back up frustrated customer already had time to figure out that he just have to make a phone call to modify order and that's not so harsh all in all.