It's a good thing that this topic has been raised coz I was thinking of something similar to this just few days ago.

I might not categorically say that the earth is 6000 years old but I will agree with you that the earth is younger than we think. Why?

Have you imagined how fast we are growing? Think about the things you were able to do in 1991 naand the things you are able to do now, just 27 years later. The growth in technology, the growth in science and the growth in human population has been massive. If the world changed this fast in just 27 years then how come it took billions of years to get to this point ? Just 27 years ago everything was analogue. And after 27 years everything has go Digital and are now in micro chips.

Why did we have to stay a billion years to effect changes that has been effected in just 27 years and so with this I wouldn't want to believe we have stayed that long on this earth. Humans are smart creatures and if indeed we have stayed a billion years, we should be living in space by now.