Because without it you can't go to the bathroom. There are 9 muscles that attach to your coccyx, enabling you to have bowel movements
I don't know what Creationist site you got that from, but sorry, there's plenty of evidence that the tailbone (and there's a reason it's called that) is vestigial.
Is the Coccyx Vestigial?
There are genetic bases, skeletal bases (the bones are the same in us and our fellow tailless apes as they are in other tailed tetrapods) and there are muscles that are useless for any other reason than a tail.
"Now muscles do just one thing. They contract (muscles are even called a contractile tissue). And when they contract, they obviously shorten. And when they shorten they pull the connection points closer together.
All of this means that when the extensor coccygis contracts it can only pull the bones it is attached to closer together. Thus it serves to flex the coccyx, causing it to extend or stick out. And this is exactly what the extensor muscle in animals with tails does. But no human can do this since the coccyx no longer moves and as noted some people don't even have an extensor coccyxis in the first place.
Yet here is a muscle stretched across fused bone joints that in other animals lifts up the tail and that in humans and other apes exists solely to move the coccyx -- something that never happens. Instead it just sits there pointlessly spanning a joint that can not move. Does that sound like a feature that was designed that way or more like the result of evolution?"
I suggest you read the whole post I linked to.
My wife and I must've been jipped because neither of us can do that.
Did you guys get gypped out of semi-prehensile toes as well? I have a bad back (thank you poorly adapted bipedalism) and would hate to bend over at the waist to pick things up. Thankfully I have some vestigial prehensileness in my toes and I can pick items up as long as I'm barefoot.
They don't. Those bones are used for mating
Assuming your Creationist source is 100% correct, wouldn't the fact that leg bones were being used for mating be the very definition of vestigial?
If you're refering to the geological column that thing is a mess, and only exists in it entirety in textbooks.
This is a lie that has been long and literally debunked for 15 years by former YEC Glenn Morton. Not only does the geological column exist, it exists in about 30 different places on the Earth.
The Entire Geologic Column in North Dakota
Can we count on you not to spread this lie any more?
On this same line of questioning, I could ask why we find millions of petrified sea shells on the tops of mountains?
Let's leave aside for a moment all the problems presented by physics and geophysics as to The Flood merely happening, much less leaving behind no evidence of it's existance and take for example marine fossils (which I think you're referring to, not all marine fossils in - yes in, not just on the tops of - mountains are "sea shells"). Plate tectonics explains how strata that were at one time marine sediment was uptrust by the movement of continental plates. In one particular case, we see that action occuring as we watch. The Himalayas continue to grow about 2 inches a year as India smashes into the Tibetan plateau... pushing the former marine sedimentary layers ever higher.
How does Flood Geology explain the fact that both the Himalayas and the Hawaiian Islands continue to grow?