You're correct, purchase commitments at retail are near universal, but the article is overweighting the pressure from Apple, or any other manufacturer and is not paying enough attention to the insidious part of sales commitments.
When you're negotiating a big resell deal the manufacturer will have a pretty good idea of what you're capable of pushing and will toss that number out there along with other breakpoint numbers for increased incentives. As an easy numbers example lets say you've got to do $1M annual to be an authorized reseller and you'll get 30 net 0 float but if you commit to $1.5M they'll do 60 day net 0 float. If you commit to $5M they'll do 90 net 0 with 5% price reduction, free shipping and $100,000 of POP. If you commit to $10m you'll get all that and they'll agree to take 1/3 of your 'dissatisfied customer' non-warranty returns. They've already got break points custom designed for you to get you to the next level of commit.
So while the repercussions are harsh, resellers, especially larger ones, often back themselves into a corner by over committing to reach greater levels of incentives. Not excusing the manufacturers, but they manage their supply chains and financials based on those commits. If somebody falls far short it has big implications upstream.
That being said, it's almost the exact same scenario that occurred in the mortgage mess. Manufacturers are willing to let resellers hang themselves with insane commitments and resellers are far too willing to take on excessive commitments to get that better deal. As long as the ball keeps rolling it's fine, but sooner or later it's guaranteed to snowball and somebody is left holding a shitload of useless contracts.
The manufacturer (Apple) can book the committed sales and count them towards revenue and the reseller (Verizon) uses those commitments in sales forecasts that affect stock prices. Just like with the mortgage mess though sooner or later the music stops and a whole bunch of people are left out.
It's all a huge mess and personally I don't think there's enough disclosure in public company reporting and too many people have their retirements riding on things nobody outside the industry understands. Traditionally these sorts of things have had minimal risk for the average person. The retail market, while enormous, has always been so fragmented that implosions in one corner didn't impact anyone else. But the sheer scale of a largely unified retail element is a big, ultra nasty, problem that's brewing. About 2/3 of the US economy is in retail sales and the financials as a sector make housing look like an incidental line item. But it's being run the exact same way as housing was...