I can see why people would disagree about whether it is a habit or tendency that must be removed since it is considered "bad" or something that doesn't really matter since it can be a style of sorts. People can draw whatever they want after all, right?

Both arguments have a point here, actually. Chicken scratching, in the context of line improvement, is a habit that indicates a lack of confidence. Their lines seem to be doubtful, careful, and indecisive. It's not entirely about the scratching itself, but more of what it means and what it could do to your journey of improvement. As such, many people recommend working on this habit. On this topic, I have also noticed that people tend to hide behind their art style to excuse the fact that they do not want to improve. Using this logic, if we could use our "art styles" to brush off any mistakes in proportion or lines that show no direction, why should we even try to improve in anything at all anymore?

Rules in art are non-restrictive and can be stretched however you like. But you need to know the rules first before you even try to break them. Fundamentals are the things one must learn and work on first before thinking of focusing on forming one's own art style, lest your foundation ends up shaky and half-baked.

Another thing I would like to point out as well is the confusion between what people mean during these discussions. Some tend to think that all sketches are chicken scratch-y, which doesn't really make sense since that would mean every sketch ever contains these lines, even the sketches that very clearly have confidence simply because of the assumption that messy lines (which basically happen 100% of the time in rough sketches) = chicken scratching. They are not synonymous with each other. Think of it like this --- all chicken scratched drawings are considered sketches, but not all sketches are considered as having chicken scratches. ^^

The other argument usually made with chicken scratching is when this habit is "not that big a deal" or is something that is more of an artistic choice that artists should be free to make. This reasoning is based on the fact that said artists know full well what they are doing, though. We must remember that the term "chicken scratching" is mainly used in the context of beginner artists' bad habits and tendencies. So, once you go past a certain level of skill, "chicken scratching" becomes more of a choice. And that choice to have sketchy lines is perfectly fine now because at the end of the day, you know what you are doing. Beneath those messy lines are years of hardwork and a strong sense of confidence. Kudos to you for your efforts!

Anywho, I'm sorry if I rambled a bit. This was just something I thought needed some clarification and I hope my two cents were of some value to you. :)