Apple made these words popular. Every time they spoke about their hardware product Mac, it just works were words they kept repeating. Focusing on making a product which just works is so very important.
It feels good when you are using a product which just works. You feel in control and overall happy when you get the software / hardware to do what you want to do.
It’s easier to down play the importance of well written software or even hardware products. Why don’t you just create something, put it out there and see how people react to it being an advice we have heard far too many times. But I hope you are not giving this advice a lot of importance. Yes, it is important to launch, but it is equally important to make sure you think through the whole user flow before releasing it.
When the user feels less in control, they leave. Only a few users will take the time to send you feedback.