Quite the contrary. I understand the feeling and the downvotes. If I read my comment as written by someone else, I'd have a strong, negative reaction. What? They don't care about my failures? Are you saying that feeling down was for nothing since I cannot keep a list of them or talking about them on Twitter? It's like when I am reading and listening to Snowflake's CEO Frank Slootman: I don't like hearing what he's saying, and that's because I would like to be the one writing what he writes. But I am not him and I am not like him (for now, at least).
I believe that considering one's strengths and weaknesses rationally and logically, examining (briefly!) things that did not work out and rejections are all necessary to improve and being aligned. But keeping a list of and sharing failures like a cake at a wedding is weak. It is weak in form, weak in substance, weak in positive expected consequences.
Modern times, which are tremendously better overall than the olden times, have brought along for some reason—and especially in the US (and the Anglo world more in general)—this idea of being vulnerable and weak as being virtuous. So you have one day the failures, one day the impostor syndrome, the following day "whatever." But I don't find any virtue in that.
Since I am neither US nor Anglo, I remember, still with goosebumps, when a colleague of mine in one of the top tech companies in the Silicon Valley said during a group meeting: "Let me share some of my failures." And he went on with a list of "failed" projects and actions of absolutely zero interest for anybody. I remember the feeling of antipathy toward what I interpreted as either manipulation (please, I am weak, be kind) or tremendously low confidence masquerading as openness to criticism. What I expect from people getting a ton of money and status is: this is what did not work, that's why (if we know why), that's what we should be next time (if we know what and how). I am also looking forward to your comments and opinions. That is strong. Not sob stories.
You wrote: "A teacher talking like that could be very harsh and damaging depending on the child" -- It is the opposite, since I am not saying that "failures" are wrong, bad, they should put you down. On the contrary, I am saying that anytime we stretch ourselves (and lamentably, sometimes even the goal is easily reachable, because life is like a box of chocolate), we can miss, get rejected, lose. As it is inevitably part of the life of the achiever—and I hope (and work towards it) all my students will be achievers in some aspects of their lives—those "failures" (getting rejected by a romantic interest, a college, a company, etc.) should be rapidly and unequivocally forgotten. I mean, can you imagine keeping a list of all the men and women who rejected you? I am already feeling the testosterone dropping like a boulder in the ocean.
I was rejected by at least 50 high-level jobs for which I felt qualified. But the problem is that for those high-level jobs, other people felt equally qualified; maybe those candidates were better or had different competencies; maybe the company wanted someone better looking or of different ethnicity. Let's try to get some material for future endeavors and then move on. That's life for achievers.
Anecdote, yes. Read what Floyd Mayweather said in the criminally underrated "Winners", by Alastair Campbell (there is a reason why the book is not called either "Failures" or "Losers"): "The key quality for a winning mindset is believing in your ability to win. From a young professional in boxing, I believed that I would end up being a great fighter and throughout the years I have done everything necessary to get there. If you believe you can do it, then everything else falls into place.". I don't see the impostor syndrome and I don't see the list of rejections.