There is a moral hazard here. By accepting that APIs are forever, you tend to be more cautious and move toward getting it right the first time. Slower is better... And also faster in the long run, as things compose. Personally, I do believe that there is one best way to do things quite often, but time constraints make people settle.

At least it is my experience building some systems.

Not sure it is always a good calculus to defer the hard thinking to later.