Question

How can Obamacare defenders insist that the law is bending health care cost curves down, when the law is just (sort of) going into effect now?

Remember, the early parts of the act were things like keeping children on health insurance plans until they are 26. If costs have been bent down despite increased costs like that, something other than Obamacare is bending that cost curve down thus far, since sign ups just started last October and the initial sign up period doesn't end until the end of this month.