Kirby Shampoo system = Drycleaning
Everyone kind of danced around what Kirby's supposed shampooer really is doing but nobody came out and said it. Kirby's dry-cleaning does have a real place and time where it is actually one of the few dry cleaning systems readily available. Not all rugs and carpets are made to be cleaned using a typical water based cleaning. You need to check out each rug and carpet first before you do any type of cleaning to make sure you are using the proper method!
This rule applies to most things you do in life now, whether you're going to dig in your yard or you plan to change your transmission fluid in you car or truck, you can't just jump into it without doing some research. You don't want to rip open a gas line nor do you want to use Mercon II in a tranny that requires Mercon V, or use synthetic, paying an arm and a leg for something that will destroy your tranny in a year when they have specifically stated not to do so, but without reading up on it one might think it's better for it.
I know this first hand, had a buddy who had a Ford tranny rebuilt, said he was going to use synthetic trans fluid, I have a program that shows all specs on all Ford vehicles from 2008 and older, his truck showed Mercon V, it specifically said to not use synthetic under any circumstances. I warned him to change it, 1 year later his transmission was getting rebuilt again! Mine which he said was ready to go any minute is still working fine in my mustang 10 years later and I'm giving it a 2nd fluid change tomorrow at 140k miles.
Many real fur fiber rugs and carpets have to be dry cleaned only, you can void your warranty or ruin your carpet or rugs by not checking.
Even if Kirby's not very effective at cleaning carpet it's probably not really meant to work on synthetic deep pile carpet. Considering it was designed back when dry cleaning was most commonly needed on natural fiber rugs and carpets it still has its tiny niche.
One comment I have to add is if your backing pad or other underlayment is getting saturated with water that is not being extracted, you better start moving faster and not letting the water have that chance to ever go that deep and also have that much water shooting out of the machine in the first place. I would recommend picking up a very cheap priced used Hoover Steam vac, newer or older makes no difference they all work great for cleaning carpets and rugs that are intended for their use.