Let's take a look at GNU tar [1] and GNU social [2] webpages as examples. The first thing they tell a user is what the project is. I would say, both of them are order of magnitude better than the yarn homepage.
1. https://www.gnu.org/software/tar/ 2. https://gnu.io/social/
Well, you can't always depend on that, and in the end of the day, nothing beats actually researching and asking around.
The GNU tools have some of the worst webpages -- and yet they are some of the most useful, and commonly used, packages.