Suppose Abel is working for Manny; Abel gets a better offer and tells Manny. Manny decides to counter.
In order for it to make sense for Manny to counter and plan-to-fire Abel, he has to be planning to hire Baker to do Abel's job, but wants to keep Abel around a while for stability and to on-board Baker.
That's enormously expensive and risky compared to just paying Abel more in the first place or to just counter-and-keep Abel. If the job is that critical, pay Abel. If it's not that critical, just let the job stay open until you hire Baker.
Taking on the severance costs to fire Abel later (and pay higher UE insurance) just to "get back at him" is self-defeating more than it could possibly hurt an employee who has just today proven he could get a higher-paying job. So, where's the "win" for any rational Manny?