It would appear that JavaScript has caught up with many of the things that MooTools was originally trying to do.
I say this not as an expert but after reading this article from over two years ago:
https://medium.com/@cpojer/breaking-the-web-with-javascript-48cc406ca98dIt seems unlikely that MooTools will be updated again.
Over time we will move on and use later generation frameworks but for now we still have websites using MooTools.
I assume it is likely with the rapid development of browsers that our sites using MooTools may become broken in similar ways described in the article.
Do we think there are still people who are willing and able to maintain MooTools in such a situation?
As a diminishing group of users it must be in our own interests to ensure MooTools can be maintained by ourselves being or learning to be those maintainers?
What do other current users think?