All the moves you accuse them of "gutting the generation" and "sell off their non-core assets" are directly related to the salary cap. That's them struggling with the fact they were in cap hell because they had
51.5% of their available cap (this is as far back as CapFriendly goes, RIP CapGeek) tied up in those five core skaters (plus a $6M Corey Crawford, who could also be considered core). They don't have to unload Niklas Hjalmarsson, Patrick Sharp, Andrew Ladd, Andrew Shaw, and Bryan Bickell if not for that salary cap hell. Giving up Teuvo Teravainen is a direct result of them having to unload Bickell's contract, which is a direct result of cap hell. All of this traces back to the fact that they have an incredibly top heavy salary cap allocation, and most of the players in that top half begin to drag. Toews being a 50-60 point player instead of a 70-80 under a $10.5M contract has an awful lot to do with their decline. As does the regression of Keith, Seabrook, and Hossa. None of them become outright awful (aside of eventually Seabrook), but Kane is the only one that doesn't have a significant decline in performance as they go thru this period.
The Saad/Panarin switcheroo was dumb, but it didn't cause them to hemorrhage assets. They
gained assets from the initial Saad trade, Panarin came for free from Europe, and then the only assets they shipped with him on the return were Tyler Motte and a 6th round pick (and they got Anton Forsberg and a 5th round pick back). That's definitely not hemorrhaging assets in the process of those trades, unless you think Tyler Motte is somehow the key here. Also, another irony here is that the reason they traded for Saad back is the type of thing you were lauding the Capitals for, treating their players like human beings. They brought Saad back because Toews wanted his friend back, and they were trying to find a way to help improve Toew's game.