They need their own journals and publications because the sponsored content they call research can't stand up to academic scrutiny. They'll flip flop on their "conclusions" all the time because different people pay their bills.
They start from an ideological position, which is based on who is paying them, and then work backwards using reactionary arguments, misrepresenting statistics and sometimes just straight up fraud
I can't emphasize this enough. Think tanks are private propaganda factories and that's literally it. They're peddlers of agenda and ideology who are not concerned with reality.