I don't know what they are smoking over there at SiteGround, but Akeeba Backup has absolutely nothing to do with caching headers in the frontend of your site. Akeeba Backup is a site backup software.
If they meant Admin Tools, ditto. We do not touch the caching headers for Joomla–generated content. Quite the contrary, our .htaccess Maker allows you to enable caching for static media files by setting their expiration time into the future. That is to say, it will help your server serve the site more efficiently and make your visitors' browsers perform fewer requests to your site.
Your issue with the dynamically generated pages, however, is unrelated to any extension.
Joomla itself always sends Cache-Control headers (also in \Joomla\Application\AbstractWebApplication::respond which is part of the Joomla! Framework) to bust the cache of any page unless you enable Joomla's cache in Global Configuration and enable the “System - Page Cache” plugin. This has been the case since Joomla 1.5 — not a typo, one point five, released sixteen years ago.
Of course is you set Joomla's Cache to Conservative and enable the “System - Page Cache” plugin you will indeed be allowing Joomla's dynamically generated pages to be cached. In this configuration SuperCache will be able to cache the pages just fine.
Nicholas K. Dionysopoulos
Lead Developer and Director
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