Captcha on Registration form

Please add captcha to this form. Captcha is already coded into the Invite form so just add it to the Registration form.

Why does this component not use the built-in Joomla captcha plugins?

I understand that captcha can be added by installing and integrating RSForms component and using that for the Registration form but this is huge overhead to provide captcha for a simple 2 field form.

Thanks!