Because (1) they can and (2) some combination of embarrassment, not yet being fully prepared to trigger the Final Healthcare Crisis leading to the single-payer plunge, and naive belief that nobody knows that twenty of their twenty-three ridiculous "coops" are either in the political morgue or will be by the end of 2016 - right on schedule:
A request by Congress for subpoenaed documents concerning the [Una]ffordable Care Act's failed co-ops has been denied by federal health officials.
And Representative Jason Chaffetz, chair of the House Oversight Committee, believes the [Commissaria]t of Health and Human Services (HHS) is deliberately withholding them so that Americans will blindly keep enrolling in the program, the Daily Caller reports.
To that extent that that is actually happening.
"Health and Human Services has not provided any valid legal reason for withholding information from this committee," said Chaffetz, a Utah Republican.
Because as far as they're concerned, they don't need one beyond "We don't wanna".
"Rather, they assert that if certain information was released publicly, it could cause consumers to think twice before enrolling in CO-OP insurance plans."
Or once, which is all such a sensibly sane demurral really requires.
Given how many such document "request" items were left on the plate of Chaffetz's predecessor, Darrell Issa, this one ought to be shaken loose sometime early in The One's fourth term. Or would have been if the GOP wasn't returning to permanent minority status next January, anyway....