When I make gems I make it a point to not have dependencies whenever possible. My exception to this rule is when I add features or patches to other libraries.
I’m not aware of any libraries that would be comparable to the left-pad incident in Ruby. I do see people re-inventing small things that exist because they didn’t take the time to learn the tools available. But I don’t see those catching on.
For the record rails-assets.org is changing hosting. Their current deal ends at the end of this month March 31st, 2016 and they’re switching to Digital Ocean.