They might not, but they are probably lobbied by doctors, hospital administrators, and insurance executives, all of whom are likely to at least skim the top medical journals.
A good chunk of the rich that foot the bill for a lot of the ACA subsidies[2], the same ones that pump money into PACs and would see money coming back into their pockets if the ACA was repealed [1], also have a vested interest in saying "meh, those journals are full of crap".
Our HMO we used at old job hated ACA. At least their representative told us that informally. Another doctor I know also does not like. Someone who is self-employed with a pre-existing condition really likes it. It was hard for them to get insurance before.
The US system certainly makes a lot of money for providers and insurances. Otherwise it would be cheaper. The money must be going somewhere. These people don't want change.
Some articles have suggested that ACA repeal poses an existential threat to rural hospitals and even the private healthcare industry, so those groups definitely care about remaining in business.
1. http://www.slate.com/blogs/moneybox/2017/01/12/obamacare_rep...
Edit: 2. If this is bullshit I sincerely want to know so I can understand all sides.