If someone poorly implements something, potential causes harm in doing so, doesn't accept that they have done so poorly and express a desire to learn and improve in future endeavors, it isn't even necessarily incorrect to express that they may not want to pursue that particular field anymore. Of course it should be done tactfully which I doubt most of the comments on Reddit did. I see this same sentiment expressed fairly often on HN in usually but not always more polite terms.
In what way is it correct or even helpful? Even if done tactfully, I have a hard time seeing that being taken by anyone as anything other than a personal attack.
The correct response would be to organize the community to create a fork that is more focused on correctness and security than on performance.
It is correct and helpful because it can prevent continued poor behavior which impacts others. Trying to protect someone's feelings only goes so far. Sometimes you have to be straight and to the point with people whether they take it as a personal attack and it hurts their feelings or not.
Whether it would be appropriate in this I case I don't know but I disagree that it is never the correct response.
> it can prevent continued poor behavior which impacts others
I highly doubt that it would do anything to prevent that continued behavior. I cannot imagine a situation in which there is not a better and more appropriate solution to mitigating poor behavior that telling people "don't participate in this field". At best you will alienate them in such a manner that alternative approaches are less feasible and at worst you convert bad behavior from being passively to actively malicious. I'd be curious if you have a concrete example for when you think this approach has been beneficial in any context.
Note, I consider revoking credentials (e.g. disbarring an attorney or revoking a medical/engineering license) to be something entirely different as there is an active endorsement that needs to be terminated. Relevancy in this case would be to removing a package from a package/dependency listing service/manager.
This is just your opinion, and not a fact or some kind of social rule. In fact, I would say that using your logic, I can say that you should never ever express your opinion on such matters again, since you clearly don't know what you are talking about. Just giving it to you straight. My opinion is fact. Respect it! Do you see the irony?
> it isn't even necessarily incorrect to express that they may not want to pursue that particular field anymore
Can I express that to people who think a volunteer project owes them anything & couldn't be arsed to implement the project's functionality themselves in the first place?
Somehow I don't think that would be a constructive use f time.