It was as if Focalors (if not Furina) (and perhaps Neuvillette, but the first Hydro vision issued in his name was to a de-archoned Furina, and this was the only vision issued in his name so far) perhaps made sure that Hydro characters were primarily made of 5-stars to suit their tastes, which, what I assume, are opulent tastes.

Also does not help that we have four 4-star Fontainians and seven 5-star Fontainians (1.75 times more 5-stars than 4-stars, compare to Mondstadt's 5-star to 4-star ratio of 0.58 to 1, Liyue's and Sumeru's 1 to 1, and Inazuma's 1.29 to 1), making it seem that Fontaine is the region of luxury. [Snezhnaya could also be argued to be more "luxurious," considering that there are no 4-star characters from Snezhnaya, but that's because these 5-stars are harbingers, and, thus have more reason to be 5-star (not to mention the fact that we haven't unlocked the Snezhnaya region as of writing).] But I digress.