In scripted environments like video games, you can train an AI based on a limited number of pre-defined actions, reading the code of the game and in this kind of environment, machine learning algorithms can make decisions based on that. In open and non-scripted environment, things are a little bit more complicated. For example, in social media AI's have to deal with fake news, self-reported data, bots and so on. You can create algorithms that are smarter enough to recognize some of them, but, remember in this case you need a lot, I mean "A LOT" of computational power to run every calculation, so at the end of the day it's incredibly expensive and at the same time with a vast percentage of errors. Usually, the most useful AIs in open environments are made by the same Company that owns the platform, because they can read their scripts that they own servers are running every time users make specific actions, understanding the quality of data and how to use it as well.