I think developed and developing is also strange. It implies an universal direction countries have to follow where reality is way more complex. We should instead stop trying to simplify countries and segregating them into categories.

Developed and developing are also terms that are arbitrary. Human Development Indices of some countries that are considered developing today exceed those of developed countries when these terms were first used.

In common use it implies a strict hierarchy in rather simplistic terms.

Should not stagnant/stagnating also be added to that list? And also a negative term (staganation is neutral)? Not every undeveloped country is developing.