Could be... Except their page (should you choose to believe it, of course) specifically addresses the advantages:
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"Advantages over Traditional GANs" : Thus, we observe that our model exhibits _better training stability_ and mode coverage.
"Why is Sampling from Denoising Diffusion Models so Slow?" : After training, we generate novel instances by sampling from noise and iteratively denoising it _in a few steps_ using our denoising diffusion GAN generator.