Whenever people see old systems still in production (say things that are over 30 years old) the assumption is that management refused to fund the replacement. But if you look at replacement projects so many of them are such dismal failures that's management's reluctance to engage in fixing stuff is understandable.
From the outside, decline always looks like a choice, because the exact form the decline takes was chosen. The issue is that all the choices are bad.
Crude oversimplification: if all you’ve ever known are slow and bloated web app UIs on mobile phones, you’re simply not going to know how to make good design/development choices outside that environment.