“When playing the main lines you are standing on the soldiers of giants, repeating moves and ideas that were found by better players than you are, and that automatically elevates you to the next level. Main lines go deeper into the middlegame than side-variations, thus the final positions are easier to handle. When this happens, your higher-ranked opponent often faces an unpleasant choice between following a theoretical line to the end, where the final position would leave him with no chances to win, and stepping aside (could be dangerous) by making an inferior move in order to avoid simplifications." - GM A. Khalifman
So, he agrees with GM Alex Yermolinsky.