Good point
If someone would invent one he will definitly go to the pass and your rite we would have know by now, but maybe he wouldn't because they'll be awared that 'change one thing, change everything'. By all means that this could be that person wouldn't even exist because of it!
I know this is a bit weird, but read this for an example:
You get born because in your moms stomach, you were the first one to get to the middle first.
So that could mean that if there was just a small change, even the tiniest change before that, you wouldn't have reached the middle first before all the other 'thousands' of sperms.
Well kinda weird but I'm just thinking, you know, time is a really confusing thing to deal with.