I mean, there's a strong confounding factor - if you're paying market rate and treating your employees well, it would be very rare that someone comes into your office with a competing offer; and if you're not, then people are likely to leave you even if they don't ask for that counteroffer.

It all depends on how you are managing the compensation growth appropriate for people who are growing in their careers - if you're doing it properly and proactively, then people won't be repeatedly coming to your office with solid evidence that the actual market rate is much higher than whatever you're paying; and if you're giving appropriate raises only when pushed to, then doing that seems to be the only way how your existing employees can continue to get paid market rate.