They are not some professor in my school, some valued colleague, or known kernel expert. They are a stranger on the internet. No, I can't be bothered to research every person that claim to have some wisdom that they won't articulate to cultivate an air of mystery.
They gave me everything to dismiss their claim.
Professors get paid, we got a pointer and a lesson for free.
Here's a free dollar. "Only one?"
They said the word "vararg". That is everything. You take that, and you say "oh shit, right, thanks for the heads up" or if you don't already know what's so special about that, you do know they obviously said that for some reason so you fucking google it.
Either way, they pointed you in the right direction, and that is helpful.
The further reading that you find so unbearable takes you exactly the same time to read something that has already been written and is just sitting out there to look up for free, as to read something you demand they write again on the spot bespoke for you.
And since as you say they aren't a proffessor or colleague you personally know and respect, why do you care if they write out a full article or just a pointer? You just said you don't trust a rando. You don't trust their full article anyway.