Comment by kibwen

Rather than attributing this to typical corporate behavior, I think there's a simpler explanation: the source code simply doesn't exist anymore. Source control wasn't especially distributed, pervasive, or reliable in the 90s (at least compared to modern standards). And it's unlikely that anyone official had the foresight to keep a copy around for the sake of digital preservation twenty years in the future, especially given the licensing/copyright issues that would probably prevent legal dissemination anyway. And even if a rogue developer had the foresight to take a copy home and stuff it in a box in the attic, that media has probably degraded to unreadability by now unless they've been actively backing it up for the past few decades.