Why base parameters to custom EventHandlers from EventArg

Question

From How to: Publish Events that Conform to .NET Framework Guidelines

Although events in classes that you define can be based on any valid delegate type, even delegates that return a value, it is generally recommended that you base your events on the .NET Framework pattern by using EventHandler, as shown in the following example.

Why? How about:

public delegate void GenericEventHandler<TType, TArgs>(TType sender, TArgs args);
public event GenericEventHandler<SomeSender, SomeArg> SomeEvent;

Answer 1

Mainly so that any method with signature (object sender, EventArgs e) can handle your event. Keep in mind that delegates are variant (covariant return types and contravariant argument types).