With respect, that's not the strategy.
The idea is that the AFL's points allocation does not represent actual value.
We can trade a bunch of picks that we weren't going to use (I.e. Have no value to us) but that have a points value to bid on a father-son. But we get in a lower pick, which might not have the equivalent points value, but has more actual value to us, because it improves the quality of the picks we are going to use.
E.g. The picks 45, 51, 61 and 70 effectively have no value for us, because we probably won't use them. But they have a points value of 800 or so, about the same as pick 22.
So if we package them up with 34 or something, and trade for Brisbane's pick 20, Brisbane get a massive increase in points for bidding, and we effectively upgrade pick 34 to pick 20 for free.
It's a win win.
The actual numbers can be ironed out, but in this sort of deal we have to lose out on points, but we don't lose in reality.