Why doesn't 'USER INSTALLATION DIRECTORY' match with the Ruby version?

Question

This question was the second part of \"What is "USER INSTALLATION DIRECTORY" in rubyGems env\" but finally it wasn\'t answered.

Now I\'m wondering why in

Answer 1

The installation directory for Gems is based on the library compatibility version of Ruby. Since Ruby 2.5.1 is library-compatible with Ruby 2.5.0, its library compatibility version is still 2.5.0.