> These days developers have to invest significant time and effort into making sure the software just runs on the constantly updated operating systems and platforms — which costs money on an ongoing basis.
What’s different today?
The Internet happened, and operating systems evolve much faster. You could buy a piece of software and run it on MS-DOS 5.0 for a long time if you didn't need networking and the software did what you wanted it to do. You didn't have to update.
Today everything is connected to the internet and exposed to threats, so the updates are much more frequent, and OS makers take advantage of this to push additional stuff and even more changes. The result is a treadmill.