Yes indeed, and if it were possible to define fields that are to be available for all entities, then one could achieve a sort of polymorphism.
Say I create a new type (called ‘LinkAll’) and then I define a field for all types (called ‘Poly’) which is a relationship to ‘LinkAll’. Suddenly, a ‘LinkAll’ entity is capable of being connected to any entity in the app/workspace. Of course, the basic implementation of this would result in the ‘LinkAll’ entity having a large number of fields (one for each entity type) but perhaps these could be combined into a generic field (called ‘Poly’).
What a feature that would be!