This is only one side of the equation. What’s the cost of not providing the feedback? Either similar negative feedback on social media, which is maybe less intense but more numerous, or the negative feeling the candidate gets from the experience, which can impede future applications or applications from friends.
I don’t know which way it tips, but looking at just the potential damage of providing feedback seems insufficient.
The cost is that you further the misery of the application experience for candidates. Keep in mind for every candidate you interview, they may have applied for anywhere between 10 to 100 other jobs. If you were in their position, you would want to have a way to improve for the next interview too.
I don’t know which way it tips, but looking at just the potential damage of providing feedback seems insufficient.