said by mattmag:
OK, I'm gonna dive into this a little and ask--- When did this become such a hot-button problem? I realize the issue, just playing devil's advocate a bit, because for decades it was pretty much standard-fare for bathroom vent fans to simply dump into the attic space. Most "older" carpenters etc that you ask about it will agree, and most also say they never saw damaging effects from the old practice.
I'm not sure where you are getting this information from. It's against most building codes and certainly a bad practice to have exhaust fans vent into the attic. They should vent directly to the outside.