I was just kiddin' with the whole DOTA thing, I don't want the whole this is not DOTA discussion again.
Thats called strategy my friend(Oak Last stand should nerfed, so thats not a point).
The thing now is that taking a portal will convert it to you, but by the time your creeps are attaking his base, an enemy Demigod already killed you: you never will damage his creep waves.