The problem is, how do you know what does not need maintaing? how do you know what's going to bite you in the future? And migrating might be a huge effort. So, the instict becomes to not pick something that is already giving you an negative signal.
I'm not saying that I fully agree with that logic, but I think it's a pretty understandable behaviour.
well when it comes to github a great window into an non-updated repository is just looking at the github issues. That will signal to you if theres maintenance to be done being ignored or if the software is of quality and maintenance isn't needed yet.
People can explicitely say it in the readme. At least that's what I'm doing (e.g. https://github.com/oxodao/micromigrations)