Every year, the complexity of software increases. First you’re running everything yourself, it’s a few thousand lines of code that handles everything on bare metal. Then it’s in an operating system, and that only becomes more complex as time goes on. And then you’re running interpreted code, and sending it across the wire, and then you’re running applications inside VMs that you’re running. Who knows how many millions of lines of code would effectively be used every time you use your computer? And it’s the same for applications: as time goes on they get updated to be more and more complex so they can do more things, and all this complexity means more interactions that could go wrong.