I'm not sure that's a Wikipedia problem, as opposed to a general sources problem. Wikipedia at least often shows proponents and critics of a given idea, while the average source just presents its own position and doesn't provide any sort of context. I'm not entirely sure what you mean by "legitimate source", I don't think I've ever seen one. Often an old book has more bias and inaccuracies in it than a blog post. I recall reading a discussion on how The Rise and Fall of the Roman Empire is no longer perceived as accurate, and few people will call that an illegitimate source. Information is hard.

All Wikipedia does half the time is reference such sources, so it's about as biased as the sources are, except it tends to combine them, and there's nothing forcing it to do so in a way that represents the true balance. That's up to the content editors. The only thing I can suggest is, if you see a problem, try to correct it.

Also, pretty much every page these days has a warning on it.

Wikipedia is great for basic coverage of a fairly broad range of topics, such as physics, psychology, linguistics, religion, biology, computer science, etc. As long as you're sticking to information that's mostly perceived as fact, as opposed to opinion. I have yet to find a source that rivals Wikipedia in this regard. Wikipedia had a huge, huge influence on information transfer for many people, I think we forgot how big of a deal it is because it's been around for so long. It's absolutely invaluable to many people.

I don't believe it's Wikipedia's job to identify answers to opinionated stances, so don't expect it to be "accurate" on things like controversial history, politics, design, etc. Those things are usually not covered accurately by anyone.