For companies that are trying to "recruit" you away from your current employer, they are already aware I would assume.

Also, it seems like it would be make sense to deny an offer/opportunity if it's less than what you're currently making and/or vesting value.

I do agree that the counter offer strategy is not always a guaranteed win - I was more curious about people using this as a way to find out their "market value" (what someone is willing to pay/offer you)