them old elves are real stupid for their age
I mean... Not for nothing are elves often depicted as hyper conservative. When you get older, you get more set in your ways, less able to cope with The New... And they've been old for a long-ass time. So they've had a lot of time to pass on their values to their children.
I could easily imagine the scars, hatreds, fears from a great war 4000 years ago
still having an effect on their society. Entire human kingdoms could have risen and fallen, and they'd still remember and tell stories about Those Four Kingdoms Wot Hated Us And Everyone We Stand For.
Add in the isolationist nature, not even
trying to look at the outside world much... It's not "stupid", per se... But a mindset that's "worked for us for two, three generations, so it should work for our kids, too." The timescale's just much,
much longer than human society's.