If you do not want your affiliates to use Dynamic link option, you can modify the template to hide the option. You can do it pretty easy. Use the template manager (Configuration> Design> Affiliate panel> Edit theme).
Find the file banner_widget_code.tpl and remove this line:
Save your modification, make sure your duplicate theme is set as default and from now on the option for dynamic links is hidden for the affiliates. To prevent from changing the themes you should remove the Panel settings from the affiliate panel as well, so affiliates can not change the main theme.