Not "effective marketing", just good supply chain management.
If any product has an initial "pent up demand", you have a several options.
- Build a large inventory of the new systems before announcement, so that you can handle the spike
- Create production capacity to handle the initial spike, then lay off people and facilities once the spike is over
- Size production capacity for the predicted long-term demand, and tell your marketing people to shout about the long initial delivery times as evidence of the "overwhelming success" of the new product.
Apple's choice is always #3....