Abstractions in Rails
Rails abstractions (Active Record, Active Job, Action Mailer, Active Storage, etc.) make it easy for developers to integrate with 3rd party service vendors without concerning about service-specific APIs.
[Rails Notes] Doubly polymorphic has_many: :through association
Double-ended polymorphic has_many: :through association in Ruby on Rails.
[Rails Notes] Rails Concerns, and an Example of Wrapping Polymorphic Association
Rails Concern can be helpful to DRY code under certain circumstances. Here is also an example of wrapping polymorphic has_many through association.