For most, it's a simple defense mechanism.

Some topics are more likely to attract assholes than others. If you don't want to be drawn into a political debate with assholes, you don't study those topics. Better to study something that can be studied without being forced to make a political stand.

That would not happen in the ideal world, where people try to avoid misinterpreting and overgeneralizing results. But controversial topics always attract people acting in bad faith. Even most of those acting in good faith are unused to the level of precision and pedantry required to make justified conclusions from data.