QuestWorld was originally created by Dr. Benton Quest as a research platform, within which various experiments could be simulated and scenarios played out without risking harm to the real world. It turns out that QuestWorld is such a real experience to its users, that should one's "avatar" die in QuestWorld, the user's brain would go into "damage control" mode for real, doing actual permanent damage to the user's body and brain. Thus, use of it becomes limited; it is impossible to, for instance, witness an atomic explosion or a supernova up close in QuestWorld, or to play out standoff or other military scenarios. Dr Quest would likely not allow his invention to be applied to the military anyway.
Johnny, of course, sees it as a toy, and largely ignores the dangers until Surd makes QuestWorld more dangerous than usual. Dr. Quest gave Dr. Surd a limited version of QuestWorld to allow Surd virtual mobility (he's portrayed in JQ as Stephen Hawking's evil opposite), which Surd hacked in order to take control over Questworld proper.