Not exctly true. Water will vaporize at a much lower temperature. Otherwise your kitchen floor would never be dry. It just takes longer at the lower temps.
It's well known that
oil has a proper operating range. That range depends on additives, dtergents, magic formulas, etc. You can easily find information about max temp. But there's not a lot of solid information telling us what the minimum temp is. It seems to be generally accepted that 180* is minimum operating temp. Although I wouldn't think that 212* is out of line, either.
Keep in mind that not matter what the thermostat is, most street cars with a cooler will have a tough time getting the
oil above 180* in routine driving. That's because the "closed" thermostat always passes about 10% of the
oil through the cooler. In the winter, I cover mine with clear duct tape so it gets warm enough. Otherwise it never gets close to 180*. If I was industrious enough, I'd make a fancy cover for it out of Lexan or something.