This is something I found to be consistent across almost all novels. Chapters with thousands of views and no comments, stories that have been running for months but only have 3-4 comments.
Uhh, there are many reasons, but in general I'd say that you can correlate it to something like a youtube video.
A youtube video with 1m views usually has roughly 100k likes/dislikes (go confirm), (not accurate on music videos due to playlist reasons). It's quite accurate to say that only 10% of viewers bother liking a video, and usually only 1-3% post comments (a bit less accurate).
Now when it comes to novels it's really quite similar. 99% of people don't leave a review on a story, but they're slightly more inclined to comment on a chapter.
If you're a new reader reading from c1->c74 which is the "newest" chapter, you're likely to breeze through all the way to c74 before you think about leaving a comment, as any "discussion" is 1year old and any comment/joke you could've made has already been posted by someone else. On top of this you kind of realize that "thanks for the chapter" wouldn't really make sense on a chapter that's 1 year old.
This type of reader is by far the most common, and even if you caught up to the fresh release, many of them either drop the novel or wait for a month to get 10 new chapters rather than reading 1 every 3 days.
We can therefore theorize that of the.. 5% of people who should normally write a comment, most will skip their comment until they catch up, leave a comment and go awol for 10 more chapters.
There's also differences in types of novels and the "impact" they have on a reader. Some novels are merely fast-food and you don't put any thought into them, while others are "quality" to the reader, making them a bit more likely to comment or leave a review as well as keep updated.
It's like comparing "Reincarnation of the Strongest Sword God" to "The Wandering Inn" > A very unfair comparison, but point proven. One of those novels will just be binge read and tossed aside, while the other has a more interested fanbase.