Individuals, groups, and organizations (some very powerful, some lone morons) on the extreme ends of political/societal spectrums use social media to manipulate disenfranchised and simple minded folks to do their bidding. Democrat, Republican, socialist, communist, libertarian, white, black, brown, green, blue, rich, poor, pick any group big or small, use the internet to sow discourse and extremist views. Some are very smart and know what they're doing in manipulating the simple minded for an end goal. Some are just fools who too easily communicate with other ignorant folks who reinforce their ignorant views and convince themselves they're not extremist idiots.
As far as extreme or middle ground thinkers, if you say things like "I'm glad when a cop dies even though I don't know anything about the cop I'm sure he did bad shit and deserved it", you are not in the middle on the subject. If you say things like "I don't care that black dude died because he was criminal in the past and that's good enough for me", you are not in the middle. You're just a "us v. them" extremist. Apply it to cops v. society, Republican v. Democrat, Muslim v. 'Merica, white v. black, etc, etc, etc. There are individuals in this world, who don't hold all the views you think they hold just because of the color of their skin, their job, their religion, or political affiliation.
Finally, the President of the United States, past, current, and/or future, shouldn't be on Twitter.