On the highest difficulties vs. AI in AoE2, turtling was really the only option. Because let's be realistic - if you're fighting outnumbered 7-to-1 by a bunch of players who get thousands of each resource every time they go up an age, you should lose and it's only by badly abusing a gap in the AI that you can win. In AoE2, that gap was that they didn't really understand how to break down a turtling player, and settled for sending modest waves at fairly regular intervals towards generally predictable points. Try that same strategy in MP AOE2 and you get smacked (as I did the first few times I tried MP).