But, so many people slam Apple for shortages or systems not being capable of a launch of this magnitude.
There are two different problems here: manufacturing and sales.
When it comes to manufacturing most competitors have solved this by having many models and a steady stream of smaller model launches resulting in a steady production rate throughout the year.
Apple has chosen the exact opposite and is causing a logistics nightmare by having one huge launch once a year causing a very uneven demand for manufacturing capacity. Others try to avoid this situation but despite the problems it does come with a nice marketing and publicity effect.
Apple could make everyone wait for six month, stockpile 35 million units and then release them all at once but that would make no financial sense. Apple could also by production capacity from Foxconn based on their peak demand although they would then have a lot of unused production capacity for most of the year and that makes no financial sense either. Or they could do what they do know which makes sense although those that have to wait for their unit are complaining for obvious reasons.
A different story is having their sales system go down when receiving 600 000 orders in one day (and now the number of models is really irrelevant, only the total volume is relevant). This is really because they have made the sales process quite complicated. I think this is the part they are now being criticized for.