But it's the other way around! That's the whole point. Every app starts out small. Apps don't grow unless you add complexity to them. It's much less work to do something simple than doing it overly complex. We see this all the time.
The question to ask should instead be: How can it be that "We spent x weeks working on increasing complexity" is not completely unsellable, if all your users want to do is pay their bills?
Now, reality is never that simple and users constantly ask for new features, that much is true. But why can we as an industry never listen to all those users who don't want new features?
It used to be completely normal to identify a need, sketch out the most appropriate funcitonality to solve that need, and them implement it. Then the core functionality is done. The software can continue to be developed around that functionality, but the core is fixed because the problem domain is well described.
No software is allowed to fit the problem domain anymore. It's just a constant pile of features upon features, to keep a legion of product designers, user experience managers, product owners, and an army of developers busy every day with no end in sight. The only break from the treadmill is the occasional product redesign, and if you can't afford that this increment then you can always change the frontend framework. Whatever happened to decent problem modelling and when you're done, you're done? Optimizing what we got instead of expanding it?