Off topic at this point, but I can at least try and answer your question from my perspective. Let's say you're building some software and you're looking for libraries to ease the burden of how much you have to write yourself.
In a vacuum, it would be fine to just look at features and call it a day. But software is aiming at a moving target. Whether you're building a web app and the browsers update out from under you, or a desktop program that needs to keep working after an OS update, or whatever your outside dependencies may be... unless you control literally everything (down to the hardware) there is going to be some level of bit rot, and you're going to have to invest in keeping your software up-to-date.
So, if $LIBRARY looks okay, but hasn't had obvious signs of maintenance, it could mean one of two things: either it doesn't need any, or the maintainer isn't active. If it's the latter, then when maintenance time comes, it'll be you that has to do the maintainer's work. Taking on that ownership might be okay, but it's something you need to be aware of when deciding to use that code for something nontrivial.
I haven't left any such comments on HN, and sometimes they might be phrased uncharitably, but I find them helpful to take into consideration.