Sir, listen to this video from 13 min to 14 min. https://youtu.be/ShNhaycQXik?si=l42Plr5z3K5RT0Vq
Also, listen to this video at 1 hour 36 minutes
Nibbāna is the Supreme truth. It cannot be only found in the Tipitaka. A noble friend(ariya) with special knowledge can help other people to see this truth in their life experience. Even if the Tipitaka disappear, as long as an ariya teaches Nibbāna in the world, it doesn’t matter. If the last ariya dies, even if the Tipitaka is there, nobody will achieve Nibbāna. This is how a Sasana end. The Kalyāṇamittasutta give hint to this idea.