That infiltrator timing. Just in time to accept metal delivery.

Because estall is the hardest thing to counter in this game.

Would you rather own the hill that wins you the game or have a yellow snack bar to look at? Building energy infrastructure takes time to pay off during which the enemy has an advantage over you.

quote: Wait, why do we need to own the hill? Why not walk around the hill and just leave 2 artillery to destroy hill units?

1) Because if your artillery isn't defended by anything, it's going to get raided and killed. (also artillery doesn't kill units, it kills porc)
2) Because there's a lot of metal in the middle.
3) Due to its location, having the middle means you can react faster to issues in the sides. Moving units quickly from one corner to the other without passing through the middle is impractical, which means you're going to lose them.