It's a possibility. For me personally, I have no problem writing a review, or even just commenting on a story. If I really enjoy a chapter, I'll leave a thought, and if I see flaws or any problem, I'll point it out and offer some advice.
But words can feel impersonal, so for some people, it can be difficult to express their thought and opinion in text form. And others might be afraid that the latter will *hurt* the writer, so they refrain themself from leaving review or comment. The truth hurts, that is true, but constructive criticism can also be of great help, so I see it as a necessity, and an inevitable part or being a writer.
And lastly, a review should also be written once a story is completed in full, which is not always the case on here, or on any similar sites.
So I hope my answer can shed a bit of light on your inquiry,
Kindly, Rin.