1. Just with the whole element of surprise ganking.
Yes, it's true that if you notice the enemy jungler trying to gank your lane, you would be playing it safe.
However, there are many games where the jungler can just dive you, chaining CC with the enemy lane and kill you. This usually occurs when the jungler gets fed, even if you didn't feed them, but your other lanes did. You can't safely prevent this gank, since your teammates decided to play badly. You can't pinpoint that on somebody because their teammate is playing badly.
These points only work if people are willing to go with it. Although I have carried games where my team fed like crazy, I can't expect to do the same every single game. At one point my teammates should be the one carrying me, or at least not making it harder on me. And that usually happens in higher elo, or just based on pure luck.