Yep, and these applications certainly do still exist. Scientific applications come to mind, probably also engineering support, and maybe financial modelling?
However, whereas they used to make up the overwhelming majority of programs, they are now minority, yet we still try to model all programs like this.
Which is obviously possible, after all we're doing it. But it's not a good idea.
It is actually my full time job to support a suite of applications that do exactly this.