Oh I can assure you, millions people in the northern europe do exactly this ;)

EDIT: I guess it depends on your definition of "humid". But 90C and regular water infusions are pretty common sauna conditions.

I mean yes it depends on your definition of humid but if your definition of humid is under 20% RH then that's not in agreement with any other humans on the planet and if it's over 50% RH then no, millions of people are not doing this because they would die. Our bedroom is at 50% RH because under that our baby's skin dries out. There's no way anyone is sitting in a 90 C 50% RH sauna for any appreciable amount of time. They would die.