https://hbr.org/2016/07/setting-the-record-straight-using-an...
Outside offers to get a raise are a risky business at best. If someone is unhappy enough to do this it isn't just compensation most of the time.
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.
It isn't the wrong call to keep someone on and counter, it is just a tricky situation.
The probability of someone leaving didn't change because of the new offer, the manager perceives a power differential and is responding to that.
If I go in with broad market data, the argument could be made that my specific circumstances make the general market data invalid.
If I go in with specific job offers, then I present myself as a risk to leaving, and the conversation may be more adversarial than I intend.
So could there be a service that sits in between? my-market-rate.example.com. Employees submit resumes, and we abstract the companies, roles, etc. Submit those resumes to companies to get an expected salary for that position and indicate interest to hire.
It is a difficult position to be in, but I think the solution is relatively obvious. If you think you are being underpaid and you don't have an open line of communication to your employer about your compensation that is the crux of the problem. If you can't comfortably discuss compensation at any time with your manager in a no judgment zone where the employer immediately assumes you are leaving then you and the employer lose. At that point you may feel the only option is a competing offer and the employer may counter, but they will be counting the days until you are gone.
A middle service could help keep things fair, but any employer you would feel comfortable using something like a `my-market-rate.example.com` service report with you probably already can just have an open discussion about compensation without any concern. I could see it being useful in some places where the organization / manager really does just lack information about fair compensation but... that strikes me as pretty uncommon. Managers tend to know far better than employees their value in the wider market and to the organization specifically.
Ultimately, you just have to do your research and if you know you are underpaid you should be able to find employment somewhere else. If you fear a comp discussion would trigger your employer firing you, time to look for another job. If you think it won't change much, time to look for another job. If you think you are close and have a good relationship with your manager, just talk about it. In my experience employees, especially in high tech, are very worried about discussing compensation and how that might be perceived by their manager. In reality many folks that generally like their place of employment and end up where they come in with a counter offer could go back in time 6 months and have a direct conversation with their manager and get a raise (or not, signalling it might be time to move on). If it takes that competitive offer to budge your employer it means they know you are worth more but they weren't willing to give it to you fairly.
Anyhow, that is my brain dump on how these things play out.
https://hbr.org/2016/09/why-people-quit-their-jobs
At the end, a research and analysis firm in this space says 50% leave within one year. I could not find the papers. I actually researched this a lot when put in a situation that we had to make a counter offer and there are some better papers and such out there, but I don't have it handy.
You have to go case by case and really understand what is motivating the individual. There is a very high chance the relationship is beyond salvaging. But there is also a good chance you can fix the problem. It is much better to never be in that situation to begin with (preventative maintenance). Regardless when you get to the point of making a counter offer anecdotal experience and research indicates it is about like flipping a coin. Maybe you can gain some insight via discussions and back story that make it better than flipping a coin, but the basic idea is you are in a relatively unpredictable situation at that point, no matter what.
Whereas, having constant and open communications with employees, discussing comp and making sure all issues stay little issues prevents these situations. Eventually someone may leave, but in my experience you can almost always remove the chance they come to you with a competitive offer. They will know where they stand with the business and be getting a fair wage or they will know it is time to move on. It is a much better relationship than an employee feeling they have no recourse but to drop a bomb on your organization.
That said, it is understandable how this happens with "line managers". e.g. middle managers. Individuals not empowered by corporate structure to do the right thing. But in orgs of less than 100 people this should never be happening.