Of Comte, Durkheim, Marx, and Weber, the people credited with the establishment of "modern" (pre WWI & WWII) sciences of society all were "political" philosphers | thinkers that looked at the behaviour of societies.
Max Weber (1864 – 1920) https://en.wikipedia.org/wiki/Max_Weber was a German of some influence, and the pre and inbetween World War periods were a time of intense political debate in France, Germany, and surrounds.
Who are "they" to whom you refer, and what is "political" as opposed to "social" ?
One might guess (and its just that, a guess) that such regimes target the social sciences first because such departments (eg economics, political studies) are adjacent to live politics, the regime's people think they understand them and can make contributions (in reality, trying to take control of course) and of course because the hard sciences require the payment of a hard tax of mathematical skills to say anything useful, which most political hacks do not have.