I've always thought why wouldn't they be more knowable in equestria, They Saved the World…….THREE FUCKING TIMES! They are practically living legends for christ sakes, Wouldn't they be spotable in equestria more often, and having more praise, hell wouldn't anyone not even give them ANY shit for what they've done to save the world?! Trixie says she's all powerful….DIDN'T YOU HEAR THAT BASICALLY THERE IS 6 PONIES THAT LIVE IN THE SAME TOWN, AND I'M PRETTY SURE EVERYONE KNOWS WHERE THEY RESIDED IN, AND YOU GO TO THAT SAME TOWN, AND ACT LIKE YOU'RE THE MOST POWERFUL MAGICIAN? I THINK I WOULD SKIP THAT TOWN, OR HELL, STOP ACTING LIKE YOUR THE MOST POWERFUL MAGICIAN!

The way I see it, no one really knows about the elements of harmony, and those who do don't really care who the bearers are; the average pony doesn't really bother with the higher order and the Canterlot Elite are too caught up with themselves.
Besides, Celestia probably doesn't go around telling ponies who the bearers are, she wants them to live normal lives without the stress of being heroes.