Part-time workers who wish they were working full time are a function of a broken economy. We have not had a recovery. That broken economy has been largely caused by endless regulations over the years that hamstring the ability of businesses to operate. Indeed, Obamacare was not the first, or only such regulation that has hurt people in practice. We have created a HUGE mess of senseless interferences in our lives that goes way beyond Obamacare. Which was why I pointed out that the a simplistic X caused Y or X didn't cause Y kind of post is vapid.
What I would say is that if correlation did imply causation, though. ... as the U-3 employment number has gotten better during Obamacare's implementation, the number of part-time workers in the U-6 number (which, for the record, suggests that the real unemployment rate in this country is well into double digits) -- has increased dramatically -- just over that time. Was it Obamacare that has caused that number (people who are stuck in part-time jobs) to increase by several percentage points each of the last 2 years?
I am sure there are people eager to argue that Obamacare had zero to do with it. ... with a million reasons why. Just as there are people who delude themselves into thinking you can mandate that employers have to pay their workers something (via a price-fixed wage or overtime pay), and not expect it to have the effect of businesses either having to go out of business or make up the increase in their input costs by hiring fewer people or employing people in a way that skirts around the thresholds for regulation.