Are you saying photon noise isn't real? That's odd because the effects of photon noise are something I (most deep-sky visual observers, for that matter) have directly experienced many times. To cut to the chase, the reason a larger aperture telescope allows the visual detection and observation of fainter (e.g. lower surface brightness) extended deep-sky objects, is that the larger total light packet delivered to the eyepiece has a - wait for it - higher signal-to-noise ratio (SNR) than a smaller aperture scope is able to deliver when pointed at the same object. The larger aperture delivers more total light from the object (galaxy, nebula, or star cluster) to the eye. Photon noise being proportional to the square root of the total light, that larger light packet has an improved SNR. As a result, lower contrast objects and details in those objects become observable.
If you ever get the chance to attend a star party at a true dark sky site, wander the field and enjoy views through as many telescopes as possible. Don't just walk past the smaller rigs. They'll offer nice views, too. But when you step up to the eyepiece of an 18-inch or larger Dob, mentally compare the view in that scope's eyepiece with the view of the same object delivered by a 10-inch or smaller instrument. It's the increased aperture, larger light packet, and improved SNR that make all the difference.