Please don't do this. I actually find these example emails much more insulting than the generic "we're going in a different direction" emails.
The reason I prefer the generic emails is that in many ways they're a testament to the fact that interviewing has a high degree of randomness. In many/most cases, rejecting a candidate comes down to an amorphous feeling that they won't fit in. Or just a brain block on a particular problem which doesn't speak to overall technical ability. Bottom line: the process is often quite random, so attempting to ascribe random decisions to inherent personal attributes is insulting.
The one kind of feedback I appreciate is when it's specific and actionable. For example: "we only hire people with an active open source presence" or "we've decided to curtail all remote hiring." This is something with a clear reason that isn't inherently personal. And no, "improve your culture fit" is not actionable.
I've seen interviewers that were worse than the candidate, knew less, made mistakes in asking questions and evaluating the answer and then rejected the candidate anyway. To get an email like from the OP after something like this would be pretty terrible.
Recruiting personnel in human resources are not in a position to evaluate the merits of the interview and it might help if this person wrote the feedback from the perspective of the interviewer and not as a collective "we".
The reason I prefer the generic emails is that in many ways they're a testament to the fact that interviewing has a high degree of randomness. In many/most cases, rejecting a candidate comes down to an amorphous feeling that they won't fit in. Or just a brain block on a particular problem which doesn't speak to overall technical ability. Bottom line: the process is often quite random, so attempting to ascribe random decisions to inherent personal attributes is insulting.
The one kind of feedback I appreciate is when it's specific and actionable. For example: "we only hire people with an active open source presence" or "we've decided to curtail all remote hiring." This is something with a clear reason that isn't inherently personal. And no, "improve your culture fit" is not actionable.