I don't see how that would make up for anything; especially given how dynamic and list-/function-oriented JavaScript, the most common language these days, is.
In a situation like that, I would be willing to assume that those who you thought were experienced were almost as lost in any event as the beginners; and no amount of language familiarity would help them.
I'd be willing to assume that the instructor and authors of the curriculum, after many years of observing such phenomena in the wild, might've anticipated your exact assumptions, and designed against it.
But yeah, on the first day of school, children tend to puff up their egos and put on airs, and some people might've exuded a soon-to-be-deflated sense of overconfidence, when they weren't actually very experienced after all.
Both are possibilities. BTW, just as those supposedly inexperienced students found out, you know what happens when you assume... right?
In a situation like that, I would be willing to assume that those who you thought were experienced were almost as lost in any event as the beginners; and no amount of language familiarity would help them.