Grew up in a continent of many legendary arahant monks (in Thailand), I would say legit lessons have been lost a lot in the past century, to the point that, as of today I don't think I can trust any living monk as a teacher, it's also very hard to find direct descendants of passed away arahant monk. We call this trustworthy monk "Forest monk" who you barely saw/see them, they were/are mostly in deep jungle.