Jeff Bridges, who plays Obadiah Stane, was born in like 1949 (he was 59 when IM1 came out). Even if you say he's a bit older, he clearly cannot have been old enough to be running around in WWII--that would make him at least in his late 80s during IM1. Which, well, he pretty clearly wasn't that old unless he was a mutant or had some really awesome life-extending medical treatment. If he was 20 years old in 1945, when the war ended, that would have made him 83 in Iron Man. Which, no. I could see him in his mid-sixties. 70? Really pushing it. 80? Hell, no. He and Howard might have been lifelong friends, but that would have been Obadiah's life, not Howard's.

Also. Who do we learn about Howard's later life from? Mostly from Tony. How old was he when his parents died? Not very; he never really knew them from an adult perspective. If we posit that Howard was a distant father (which is pretty certain from Tony's own remarks), then he doesn't even have much of a child's perspective on Howard. Where does he get his information on his father? Why, from his father's lifelong friend and business partner, trusty Obadiah! Might Obadiah, er, shade the truth when speaking to young Tony about his father? Might Obadiah tell him only things which would get Tony thinking in the direction Obadiah wanted him to (i.e. weapons)? Might Obadiah have told many touching stories about how close he and Howard had been to influence Tony to keep him on as a pseudo-parental figure? Oh hell yes.