It's not fearmongering, it's because anybody can edit it, and those edits are not peer reviewed. So using Wikipedia as a reference is really bad: whoever told you otherwise should be fired.
What you can do though is learn the big lines of a topic on it, because there is a lot of information on there after all, and then use some of the references on Wikipedia itself to deepen your knowledge.
This is especially relevant for hot topics, pop stuff, history, or for example anything that is up to interpretation. Other topics, like the more sciency ones, are a bit safer as references are more solid, and few would bother sabotaging the math (and if you understand it, you can check if it holds), but you should still check the references and publishes papers/books instead of citing Wikipedia.
