https://www.dreamsongs.com/RiseOfWorseIsBetter.html
It doesn't explain _why_ simple implementation is more important than having a simple interface, but it just makes an observation that simple implementation usually wins.
In my experiments simple implementation won for velocity, because quite often I need to change small parts in all the implementation no matter how modular / reusable code I'm trying to write.
As my velocity increases testing becomes more important as well (especially integration testing), as there are more features interacting in a small amount of code.