The conclusion to draw from this is that you shouldn't draw conclusions on broadly general situations that you know nothing about, not that you should draw conclusions that are likely wrong anyway.

"MBAs are bad for startups" or "Dalton Caldwell is full of shit" or "All of parent poster's startups have failed; why should we listen to him?" are not useful conclusions. Exactly what actionable intelligence have you gained from them, other than the fact that you have gained no actionable intelligence? If you take "MBAs are bad for startups" at face value, all you do is disqualify a number of candidates who might otherwise be good. If you take "Dalton Caldwell is full of shit" at face value, all you do is disqualify a bunch of information that might come in handy at some point. If you take "All of parent poster's startups have failed" at face value, ditto.

Rather, the useful information is in the supporting details. You can take Dalton's statement that "MBAs think they are beautiful, unique snowflakes that must be better than their peers", and then when you're sitting across the interview table from an MBA, determine whether this MBA believes he's a beautiful, unique snowflake. You have a lot more information at that point, namely his answers to the interview questions, his past work experience, and just the general vibe in the room. Similarly, you can take the parent poster's assertion that he learned things with his MBA, but that doesn't take away from his basic technical skills, and factor that information into your evaluation. It's about having multiple perspectives available to you to decide a specific situation, not about drawing broad conclusions that are ultimately useless.