Facebook doesn't really enable populism as much as it centralizes on populism. On a common platform, opinions and news can spread very quickly. Faster than people have time to rationally digest and or to determine what they're reading is accurate or not.

Facebook is really a perfect tool for people like Soros. You can promote whatever news or opinion you want if you have the money, targeting whichever group you want.

Anyone with a big enough bank account can take advantage of this centralized platform to influence people on a vast scale.