a departure from what is normal, usual, or expected, typically an unwelcome one
This is not meant be an insult or even a critism but more just a statement of how it probably is. It’s also not necessarily a bad thing although the use of the word aberration usually is as the the second part of the citation above states.
Ryan Dahl himself has said that he left Node behind as he felt that golang provided a better solution the issue of concurreny: https://medium.com/@imior/10-things-i-regret-about-node-js-ryan-dahl-2ba71ff6b4dc
Perhaps if he stayed in charge of the languages development things would be different but I'm not sure if that would be for better or worse. From what I understand Ryan was for callbacks and against promises. I think he has since changed his stance but from what I read, there are still a minority of node developers who believe node should be callbacks alone and if you organize your code correctly callbacks are easy to read – perhaps they are right.
Both callbacks and promises seem very unintuitive to those not used to them and fit with the term abberation in that you need to think differently to the previously traditional ways of doing things. I have been happy to adopt async await as I am pretty comfortable with that from C# at this stage.
I think Node has helped a lot of people to get started with programming as it is so easy to get going. Issues are being ironed out as I speak.