The Black Garden isn't necessarily on Mars in a physical sense or at the point in time the events are happening. Remember we had to take a portal to get there and didn't just walk over. Also recall that Dinklebot says "we're not anywhere in known space and time." There's a lot more evidence suggesting that the Vex are a race of sentient beings so advanced that they have woven themselves into the fabric of space and time. Time travel features very prominently with almost anything the Vex do. Why would the Traveler have endowed terraforming machines with this kind of power? Also, don't forget that the Ishtar collective was researching the Vex. If the Traveler had clearly made them for terraforming, those Golden Age geniuses would've seen that with their own eyes, wouldn't they? Instead they're dealing with Vex time travel and reality simulation (see the grimoire cards). You also didn't address at all the very high likelihood that the Traveler is actually the Darkness and brought it on. See some of the grimoire cards (one on the Black Garden in particular, where the dream Ghost says you are a bringer of death not Light). There's also that early play tester leak etc. In short, there's a lot of unknown with the Destiny universe but enough hints and indications in the grimoire to lead us to the conclusion that your timeline is almost certainly false. And so many people answered "accurate". Looks like not many people actually read the grimoire cards!