Because there's nothing similar at all about the situations.
Kane and Toews just started making 10.5M per season this year. They have literally zero cap space and that's with Keith being signed to an amazing deal, Hjalmarsson having a very friendly contract, and a crazy influx of cheap, young talent to work with.
The Penguins have Crosby, Malkin, and Kessel. Well, look at the rest of the team. There's a reason the Penguins haven't done anything since 2009.
The Stars have Benn, Seguin, Sharp, and Spezza. Great. They have 1M in cap space and haven't invested a ton into their defence corps while also having cheap, young talent up front aside from the mentioned 4.
We have 10M in cap space, but next season EJ's deal kicks in, and we're going to need to extend MacKinnon and Barrie. That'll be 9-10M right there. We also don't have the luxury of having cheap, young talent to work with. It's starting with players like Zadorov, Grigorenko, Rantanen, Everberg, and hopefully down the line Bigras, Bleackley, Meloche, etc. Sure this team could have kept Stastny but he didn't want to play 3C here. Duchene was already a C and he knew all along the plan was for MacKinnon to move to C, so I don't blame him for wanting to leave. The O'Reilly decision, while I've always maintained there was a choice, he simply priced himself out of here. We would have needed to trade Duchene to make it work with him and management did not want to do that.
MacKinnon, Duchene, Landeskog, EJ, Barrie, and Varlamov. That's 6 core players. How many more do you want? Teams don't usually have that many core players. The Hawks have Toews, Kane, Hossa, Keith, Seabrook, and Hjalmarsson. 6 core players. Everyone else is on the roster to fit with them and built around them.
If you're going to look for something to pinpoint on this management team, then point to the fact that the supporting cast just doesn't fit with the core players on this roster. Management has tried to bring players in and make necessary moves to make this team better, I'm not faulting them for a lack of effort, but the pieces don't fit. That's where the problem lies with this team. Not the fact that we didn't keep Stastny and O'Reilly