Buckforme, I am not sure that I understand your question?
"How do you know very few people use them."
I never stated that very few people use them, if that is what you mean.
If you were refering to to my comments on the downrange ke, and accuracy of a crossbow, here are my answers to that.
1.KE- it is simple physics, you are dealing with an object(crossbow bolt) that has less weight(usually), is shorter in length(always), which makes it less stable in flight(always). Both of these factors can, and do diminish ke, both right out of the weapon, and downrange, as well.
As far as accuracy of a crossbow goes, while it is unarguably easier to get proficient with a crossbow, real, serious accuracy is not achievable with one, due to the short length, hence less stable flight of a crossbow bolt. If anyone refuses to agree with my stance on the accuracy issue, that is fine. Let me put it this way....go find the person that you know to be the BEST crossbow shooter you know, then contact me with a time and location where we can have a little accuracy contest. Lets say, 10-50yds. You may not use a benchrest to shoot from. Bring all the money you can afford to lose, I will furnish you with gas money for the ride home.
OK, why do I prefer to hunt with a conventional bow, instead of a crossbow. Well, when I started bowhunting, crossbows were never mentioned as a weapon for archery hunting. And compounds were not commercially available. I think they were invented by 1972, but not available yet.(not sure on that) So, I started with a recurve, progressed to a compound, and I am probably going to revert back to the recurve in the near future. I have shot crossbows, I have seen many crossbows shot, I know several people who use them for hunting. In my home state of PA, you can easily aquire a doctors permit for one. I am not sure what physical limitations you must meet to get one, I think you must have a runny nose for two consecutive days.<img src=icon_smile_big.gif border=0 align=middle>OK, maybe a little more than that, but not much more. So, back to your question, I prefer to use a conventional bow because, regardless of the amount of fancy gadgets you put on a compound bow(not including a drawlock) they are still much more challenging, IMO, than a crossbow. I still stand behind my statement that a crossbow is not hand drawn, not hand held, so it does not belong in regular archery season.
I don`t mean to state, or imply that people who use a crossbow are any less of a hunter, or inferior in any way, to someone who uses conventional archery gear, you still need to get close, and go undetected. I Just don`t agree with using them in archery season.