The biggest issue I have with this take is that the author's distinction between moral "competence" and "incompetence", from what I've read, doesn't really have anything to do with a moral or ethical system. It seems like his morally incompetent have admirable moral intentions (help depressed people with CBT), but suffer basically from implementation failures. They don't know how to help effectively, and are taking all of wrong lessons from working in tech (searching for direct & measurable impact, searching for technological solutions etc) and could probably be gently taught how to help more effectively. Dividing the world of people who want to help into binary 'competent' and 'incompetent' groups will just serve to discourage people who want to help but don't know how.
I also don't feel like I have a sense of what a 'morally competent person' actually does, or how they design strategies to help effectively. The article feels like a lot of unfortunate self-flagellation for being 'morally incompetent' and not as much constructive dialog about how to actually help better.
Edit: To OP - maybe there is a perspective where you don't have to be so down on yourself here? Maybe this idea 'failed' from a cashflow & user acquisition perspective, but if it helped all of the people who downloaded and used the app, didn't you do good in the world? Maybe you didn't do good at billion dollar scale, but does that matter if you improved people's lives?