Yeah but the other teams they are "battling" with for will also sell. And in some cases, probably actively tank (via healthy scratches or shutting down guys with minor injuries). I don't know that the Flyers will. Heck, the Flyers being the Flyers it still wouldn't surprise me if they suddenly turned around and extended Giroux, or just botched the deadline in some other way (either by keeping someone they shouldn't or taking back a vet).
Sometimes you start winning games you're not supposed after you give up trying too. Blazers are 4-0 in the NBA since they became "sellers," though the cap situation in that league means you can't just take back picks/youngsters, so they wound up with some guys who can play.