Yeah, I think people just want to find that perfect solution when doing hypothetical trades, where team A is deep on D and team B is deep on F, and there is a deal to be had, but in reality, there are very seldom trades like that.
Leafs fans are constantly looking to trade Nylander for a D, which sounds nice, but what team is so deep on RHD that they have a high end one they are willing to move?
Hamilton moved, but Calgary wanted a LHD back in that trade because they weren't deep enough to simply move a D for a forward.
In this case, I think unless Montreal is trading Petry for mostly picks, chances are a team that is deeper in D prospects, and is a little more under the gun would make more sense. Dallas likely wants to push for the playoffs this year, and Heiskanen might make them more willing to move on from Honka. Calgary lost Hamonic for a bit, and he hasn't been that great for them, so maybe they would be willing to move Andersen. Those teams being out west probably makes the deal even more favourable for Montreal, and those teams can probably afford the cost a little better (or at least may be more willing to pay it for different reasons).