Dot 4 or Dot 5 Brake Fliud?

Maybe showing my ignorance here, but why would Dot 5(or any other) brake fluid be used for TOB?
I know we are only talking brakes here, but I have seen dot 5 eat the seals out of several throw out bearings. I have nothing to base my opinion on other than a guess, but I would guess a silicon based fluid isn't compatible in every brake caliper out there. Maybe I'm wrong. But I know 5 voids the warranty on more than one TOB manufacturer. Just something to ponder.