Replacing leanto log books...

On my last few hikes I've noticed that many leantos no longer have log books. I prefer a tent, but when I pass a shelter I like to see who came before me and what they had to say. Most recent, I did an overnight at Echo Lake a few weeks ago and neither of the leantos coming in from Platte Clove had a book, nor did the one at the lake, but that's not the only example.



Is there anything wrong with packing some comp books when planning a hike past a shelter? Or, like trail maintenance, cairn building, fire rings, etc., is it something that should be left to the official caretakers?