The Fried parameter, r0, should not be viewed as something inherent in the atmosphere, but it can be viewed as a property of the wavefront entering the telescope: the wavefront will comprise independent patches with diameter approximately r0. You can then use that r0 value to characterize the seeing - and this is done today at professional observatories with devices such as a DIMM. An example is here.
There are many other examples and Fried's work continues to be cited. Note that the temporal behavior of the wavefront is separate from the spatial behavior, which is defined by r0. The temporal behavior depends on the speed of the winds and can vary - but the speckle pattern can usually be seen by the eye at high power, and captured by video at a relatively low rate. The appearance of speckles is a direct indication of those "seeing cells" - in terms of independent patches of wavefront entering the telescope.
So there is nothing "hype-y" about referring to r0 = 4" - but I agree it is misleading to say there are 4" blobs in the atmosphere that cause it. Instead there is a turbulent atmosphere that ends up producing independent patches across the entrance pupil that are about 4" diameter.
But even if you agree that the Fried parameter is a useful characterization of seeing, it is still incorrect to conclude that the best you can do is with an aperture equal to r0. The theory doesn't say that at all - so for an ad to imply that such a small aperture is best would just be incorrect, rather than hype.