I heard that yogurt with probiotics is beneficial if we have one serving everyday. But any more than that might actually be bad. I heard a doctor talking about this on TV. She said that our stomach and digestive system have a certain flora, meaning a certain amount of beneficial bacteria living in it. If we overdo probiotic yogurts, we might disturb that flora which might cause problems with out digestive system.
I think people might overdo probiotics when they are on this diet. If I were following the yogurt diet, I think I would have a variety of yogurts, some with probiotics and some without, to balance it out.