Apple created the situation for themselves, though.
They started out with a goal to remove versions and upgrades, and create a buy-once-for-life ecosystem. Prior to this the productivity software market relied on upgrade cycles for steady income to fund upgrades.
They encouraged low pricing with a claim that what you lost out in individual sales would be made up for in volume, and you got apps providing 90% of the functionality of desktop apps for a tenth of the price... with free upgrades for life instead of a £50 or more every year or two.
They set up this gold rush race to the bottom, which led to a massive marketplace of "ad supported" apps when they must have known that the market wouldn't support it, and devs the world over wasted innumerable person-years making software that no-one ever got properly paid for.
The only people who ever benefited from this setup were Apple. They made lots of money from cheap app sales. They made lots of money from advertising. Because they were the ones who had scale -- while everyone else got a miniscule slice of the pie, they got 30%. And the reason I have an iPhone is not because I wanted an iPhone, but because I was given an iPad as a gift, and I bought apps for many thinks (mostly sound, video and programming) that I liked, and I didn't want to have to buy them again on Android, or hunt around for suitable substitutes if they weren't available. So I give money to Apple to avoid having to give money to the people who made the apps I use.
It's a messed up market, and it was never sustainable. That's why apps have moved more and more towards subscription models -- it's the only revenue stream that stays (mostly) open to them.
Yes, it's also happening in the desktop space, but as yet on a smaller scale. The death of physical media coupled with the increasing confidence that Windows 10 is going to offer the long-term stability that Microsoft promised at its launch is also probably making desktop app devs worried that for most users a license-for-life will end up being treated as such, rather than buying into an upgrade to get round backwards compatibility bugs in their OS.
So yes, the market was going that way, but Apple accelerated it, and they created a rod for their own back.