President Obama’s Council of Economic Advisers (CEA) has issued its valedictory report on the state of Obamacare. The gist of its argument is that Obamacare is doing fine, on the verge of overcoming its growing pains since 2014. Critics (like me) who suspect the 25 percent increase in premiums for 2017 are a problem are off-base, according to the CEA. In a normal insurance market, such an increase would indicate a “death spiral”: The sick enroll and the healthy stay away, causing next year’s premiums to increase. The cycle repeats itself until only the sickest enroll. The CEA asserts this...