Why does DependencyObject use a weak-typing EffectiveValueEntry[] array to store property values?

[zwcloud]

When reading the code of DependencyObject, I found the actual value of every property is saved in DependencyObject._effectiveValues

Why WPF choose to use weak typing object to store property value in EffectiveValueEntry.Value which is of type object?

Is the main purpose to use less memory to use an object weak type?

But we can actually use EffectiveValueEntry_Int, EffectiveValueEntry_Float and so on to keep the type of property values and avoid boxing:

abstract class EffectiveValueEntry {
    public int PropertyIndex {get;set;}
    //...
}

class EffectiveValueEntry_Int : EffectiveValueEntry{
  interal int Value {get;set;}
  //...
}

class EffectiveValueEntry_Float : EffectiveValueEntry{
  interal float Value {get;set;}
  //...
}

Or is it just a design error, may be caused by historical reasons?