Popularity has nothing to do with it. This is happening because they waited so late to start pre-orders. Usually they start in June and at least the first day you can land a pre-order for several hours if not the whole day. We'd have been through several waves by now in the process but because they waited everything is condensed. I don't doubt the Xbox pre-order will go just as quick.
my thing is this sony thing is a mess and nothing to brag about. Majority of the activity was pure FOMO, not like an organzed iPhone release where sites are crashing. This was literally people frantically scrambling to find random drops. IT will only be an issue if the Xbox release is organized and nobody cops lol, and there is no way to tell that until pre order numbers come out