IP Banning WP vs Non-WP Edition

That option is only in the Pro and Pro+ Edition.
In the WP+ Edition, there’s a rate-limiting option in the Access Control page, but that’s a different feature.

Is there a reason it doesn’t exist in the WP editions?

That feature is not available in the WP/WP+ editions because it doesn’t scale well with WordPress. That’s why we implemented Syslog logging to replace it: https://blog.nintechnet.com/syslog-logging-with-ninjafirewall/

It is still available in the Pro/Pro+ editions because there were released a couple of years before the WP/WP+ ones.