Thing is when you face against a team with mostly AP champions or a team with a lot of CC abilities you will need some MR and Resilience to reduce damage and durations on your champ. You should always build to counter the enemy team. 3 dorans blade is actually good early game as it will give you more dmg, life steal, and health. While you farm you can sell the dorans to buy items you need. You will see a lot of top tier players buying 3 dorans blades or rings early game because it is effective early game. Sometimes you wont even need armor or magic pen depending on the other teams build. Always pay attention the items enemy champions buy.