Can we normalize constructive comments?

One of the big aspects of fanfiction for a lot of people is writing for the community for various reasons. Fanfic writers also get the benefit of learning how to write or improving their writing skills / English. In general, writers typically want their work to be fluid or enjoyable and enjoy positive comments.

Can we please normalize constructive comments as well? If someone is engaging and actively enjoying the story, then suddenly stops commenting with no context because they no longer want to follow the story, or decides to stop reading, and it isn't for personal reasons, I think it would be polite for them to leave a criticism. If the writer is doing something unfavorable or distasteful and could genuinely improve, I think a comment would be preferable rather than silently walking out. If the author is doing something objectively wrong or outright offensive, especially when representing health conditions, it's time to speak up.

I know a majority of DNF results in a lack of interest or lack of time, but I think more constructive criticism is in order.