High temperature red silicone around the inducer exhaust...required?

I have a Trane 80% furnace. There is a fiberglass/felt type gasket between the inducer and the furnace itself. Is it required to have this high temperature red silicone applied where the inducer meets the exhaust flue? Or is it really a "just in case" type of thing

source https://hvac-talk.com/vbb/showthread.php?2222081-High-temperature-red-silicone-around-the-inducer-exhaust-required&goto=newpost