As far as its actual effectiveness, it doesn't seem meaningful to involk anecdotal data (i.e. "I've seen counter examples") as the parent post isn't stating that you must, but rather it's a generally good idea or a hack.
Given the data around interviewers making pass/reject decisions within the first few minutes of an interview, I would find it surprising if it wasn't true.
This is ludicrous, given that an interview and a tech talk are completely different things. In particular, an interviewer doesn't generally expect or hope to learn anything useful during an interview. That difference alone makes the situations not comparable.
it doesn't seem meaningful to involk anecdotal data
That anecdote is the only bit of data at hand. The comparison to interviews is mere wild speculation.
Really? then why are they always asking questions? :p
The effect is supposedly about lighting up the reptilian brain, and you can drop further limbic system boosts throughout your talk to raise arousal level (heart rate, adrenaline) of your audience, which supposedly keeps their interest high. I learnt this on a demo course, perhaps it's just obvious didactic technique.
I should add it's obviously high stakes but can really make your talk stand out, especially if your talk is within a series of conventionally structured talks.
1. I simply don't think its true - there have been many talks where I have become interested 10 minutes in.
2. It puts tremendous pressure on the speaker for some kind of fireworks in their first 10 seconds.
Your 10 seconds went badly? Who cares just make sure the next 10 seconds are interesting, or the next.