1st claim: Possible yes, recommended, absolutely no
2nd claim: Those vintage pictures are ridiculous in today's context
3rd claim: Straight bars allow far more manoverability than drop bars ever could. On very technical terrain, drop bars are a liability.

I can't see any merit to any of these claims. The first one is sheer opinion though its stated as an indisputable fact. The 2nd is just stupid, because the same trails that were ridden when drop bars were en vogue are the same trails many are riding today. Obviously if you are a freerider, you don't want drops, but for the casual XC rider, they are more than adequate/safe/comfortable/efficient... 3rd, I used to run a NORBA Nationals course (Waco, TX... a very technical course) with drop bars, without any issues whatsoever rocks, drops, climb after climb, no problems. You sound an awful lot like someone who hasn't actually used drop bars on an MTB making claims without having any first hand experience. Bikes are as subject to fashion as anything else. Drop bars are out of style, but it doesn't mean that they don't work. Heck, Nashbar and On-One has seen the need to bring back the mustache drop bars, which a lot of riders are using off road these days. Particularly on singlespeeds.