为什么在.net中读取/写入属性不能覆盖readonly属性？

Public Class Base

    Protected _name As String
    Public Overridable ReadOnly Property Name() As String
        Get
            return _name
        End Get
    End Property

End Class

Public Class Derived
    Inherits Base

    Public Overrides Property Name() As String
        Get
            Return MyBase.Name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property

End Class

Why is it impossible to override a getter-only property and add a setter?