Dropper posts are rigid by design. The advantage of a 27.2 carbon post is that it has flex built in to provide compliance. By adding a rigid dropper post, you remove that compliance. With ActiveRide, we can keep a rigid post at full top-out but give the rider compliance in any of the settings below full top-out, providing the best of both worlds.
Check out the Reverb AXS XPLR User Manual found on the SRAM Service Site for additional information.