Make CRM_Contact_Form_Search_Custom_Base abstract?

If you want to create a custom search, you have to subclass CRM_Contact_Form_Search_Custom_Base, and implement the functions all, from, and where. The easiest way to do this, is probably by using civix.

But if you have to implement those functions anyway, wouldn't it be a good idea to make CRM_Contact_Form_Search_Custom_Base an abstract class, and all, from, and where abstract methods? Or am I overlooking something?