When its done well its not called backtracking, its called exploration and adventure.
Metroid prime has examples of both.
You go all over the same areas to get to new areas and new powers during the course of the game. Nobody called it backtracking, it was exploring and adventuring.
It didnt start getting called backtracking until you had to get the chozo artifacts, which lead you to no new areas, and gave you nothing new in return, and were literally nothing more than keys.
Destroyed the pacing of the game too.
Its a testament to the rest of the game that it was still as fantastic as it was, even with the grocery list of keys you had go back and pick up at the end.