Did you carefully read [1]?
As noted by others many WP users don’t have access to the webserver or lack knowledge to configure it properly.
As noted by others many WP users don’t have access to the webserver or lack knowledge to configure it properly.
As someone who has written their own WP caching plugin, it's actually very convenient to perform the caching in PHP, because you can check for cookies and regex expressions for URLs, and there are many plugins that handle it well. For most sites I use a free one called Cache Enabler.