With webform 3.x, any content type can be made webform-enabled. Thus, the webform content type itself is not always necessary.
If you make "Page" webform-enabled, and remove the webform content type, Mollom throws the following errors when you're configuring a new form:
Notice: Undefined index: edit any webform content in mollom_admin_configure_form() (line 211 of /sites/all/modules/mollom/mollom.admin.inc).
Notice: Undefined index: edit any webform content in mollom_admin_configure_form() (line 213 of /sites/all/modules/mollom/mollom.admin.inc).
There's also an empty list item in the help text below ("Bypass Mollom protection on forms," "Edit all webform submissions," [blank]).