I think it’s quite misleading and dismissive to use the word “easiest” to characterize the endgame. While one might argue that it could be “easier” (in some sense) than earlier parts of the game, since thorough, systematic analysis can become tractable, I still don’t think one should suggest that it is “easy”.
I thought that I had a pretty good grasp on the end game, since I was aware of some concepts like double-sente, reverse-sente, etc. However, my recent introduction to the concepts presented in the articles that I linked to earlier made me realize that there was a whole new layer of strategic depth and complexity that I was not aware of.
I’m amazed by this endgame problem that was devised by Berlekamp and Wolfe (white to move and win):
It would appear to be rather straightforward to handle, since it seems like there are bunch of equivalently valued endgame moves. However, finding the optimal line of play requires precise analysis (newly developed by Berlekamp and Wolfe). They managed to even stump several 9-dan professionals with this problem (before they taught them the new analysis techniques).