It's big in Europe, as already stated because Germany has a law making it so that the tire can't go past the fender (Also one of the reason why widebody is so popular there) so if you want deep-dish rims you go for the stretched look to stay compliant. It has some performance benefits such as stiff sidewalls for high-speed control, but also has some downsides, like lower contact patch for a heavier wheel. I don't know of anyone that would do it though, if you know of a Butler tire though, go and see if they will. The one nearest me has done some weirder stuff before, so they might be willing to try it. The shops are just afraid you're gonna shred your tire and sue them when you have a blowout. See if you can get them to do it by signing a liability waiver.