I claim that it is trivial, albeit obnoxious, to dismiss most informal utterances in the way you have just done. This is because informal language is complex and enthymeme in the extreme -- we don't tend to articulate every e.g. assumption and premise and contextual relation up front in every utterance. Language is messy because the concepts under discussion are complex and messy, and vibes are powerful tools for wrangling that complexity and getting at meaning. And the majority of paradoxes and contradictions one can identify carry no signal whatsoever. Perfectly reasonable statements can be rife with them.
For example: my interpretation of what the parent wrote was something like "the 'making stupid mistakes' line together with the rest of the blog post signal towards neurodivergence, and someone who is harshly self-critical. so with urgency, I warn the author to be weary of comments on HN, as there is a strong likelihood of being led down an unhelpful path that might aggravate this, particularly given the harsh self-talk and what we know about the subcultures that frequent this place"
Speaking of unarticulated contextual relations, "I often make careless mistakes" is literally in the DSM-V as a diagnostic criterion for ADHD.