Neither Boston's problems or Vancouver's were Armstrong's problem. Especially Vancouver's.
Boston has a ton of flexibility (that they haven't been able to use, ... yet), so I don't think it was a particularly crazy ask for the best defenseman available outside of AP. But I don't necessarily blame Boston for waiting it out and seeing what is out there. Hall or AP aren't fantasyland adds for them. It's entirely possible to add Hall and deal DeBrusk for a defenseman or add Pietrangelo and deal Carlo for a forward, instead of tying up that flexibility in OEL and dishing out assets on top. But they also had a chance with free agency to find a bandaid solution for forward depth, even if Studnicka was dealt.
It's probably why Armstrong was frustrated by the agent "deadline". Sweeney probably said something like, "You know that's not completely crazy, but let's revisit a stronger offer after free agency dust settles. For now, this is the best we can do", and Armstrong liked Studnicka better than anything else on the table, so he was prepared to wait.
For Vancouver, their cap problems and terrible contracts aren't the Coyotes problem. They also have a near-zero chance for AP, and I'm sure Benning is aware of it. They could have put a franchise player into their D core and turned their lack of depth into a position of strength there with Hughes and OEL on different pairings. A deal also would have cleared out one of their bad contracts. It's not crazy to ask for their best magic bean, and I find the fans' adamant refusal was a bit weird considering their situation. I think they were brainwashed by a media/twitter echo chamber that the Coyotes had to move OEL for whatever Benning would offer, and some sort of bizarre PTSD from the Kesler situation and a belief it was their chance to exact "revenge" on someone. "It's our turn now!" The situations were completely different. And dealing with a potential cap squeeze in four years if OEL takes a turn for the worse, is a hell of a lot more attractive than whatever they are facing today.
But everyone looks more or less happy with how it turned out (except probably Benning).