I looked around online a bit on some more commercial types of flat tops - not the giant ones that go in a big restaurant, but food service type ones that are similar sizes to the Blackstones. Looks like the tops can be cast iron or typical carbon steel as well as stainless. What I saw in a similar size and price range has a thickness of 8-10mm.
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Similar to cooking a steak in a heavy cast iron pan, the thickness of the cooking surface equates to thermal mass and heat transferred into the food and can dramatically impact the final result. Not knocking the Blackstone griddles but the 1/8" thickness doesn't seem all that impressive to me nor does the heat distribution. Granted, the 2nd photo is a 25mm plate, but you can easily expect a significant cooking difference with the increased plate thickness beyond 1/8".