The notion that Territory is Duchy is beyond wrong as the strength of the card is highly sensitive to the game-state and Kingdom.
The main thing the strength of the card is sensitive to is whether you want to pay $6 for a Duchy that may or may not come with a Gold or two (that you may or may not want).
Same with Warlord. It can be highly centralizing in some Kingdoms (Caravan totally sucks with Warlord) and it can be pretty weak.
It's highly centralizing in 90-93% of kingdoms. It's not super impressive in a big money kingdom where you probably aren't playing more than one copy of an Action card per turn anyway, but those kingdoms are rare, and even in those games, two Warlords just for the non-terminal draw is decent because what else are you going to do with your $5 turns.
Ironically Battle Plan is the only robust card, you always want two copies. It is above all a conditional Lab, that it can rarely manipulate the pile in your favor is mostly irrelevant.
The fact that it manipulates the pile in your favor is extremely relevant. Gaining a third Warlord, or gaining two and preventing your opponent from gaining the last one by manipulating the pile gives you like a 70% winrate. If you gain all four, that's like an 87% winrate — in the average kingdom, including the ones where it's unimpressive. (There's causality in both directions obviously; if you're winning anyway, you can more easily win the split. However, the fact that top players will often actually spend their early game advantage on winning the Warlord split still goes to show that it is important to do so.)