Serve Cache Only via PHP – Why?

The version 1.0.4 update of WP Fastest Cache included the ability to serve cache only via PHP instead of serving via htaccess by modifying the wp-config.php file.

My question isn’t about how to do this but rather why to do this. What are the pros/cons of doing this? Is this only for special situations or any wordpress site?

I’m just trying to understand what this does and why I should or should not do this?

Thanks for your help

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