I remember reading an interview with Bill Gates about how "two way mirror" user testing where devs watch REAL users interact with their application is both incredibly important and humbling at the same time.
The above quote is from the days where people bought shrink wrapped software so it was incredibly hard to observe people using your application in the wild. Therefore, companies spent money to do it in house to get better data.
Modern web applications, I would argue, make observing user behaviour in real time trivially easy but I'm sure lots of companies don't even bother. In turn, this brings us to the incredibly complicated interfaces we have today.