Some people say that you should take for granted for opinions on Reddit, because comparing it to academic journals is like comparing kindergarten to university. But I don't understand. Well, it's true that it is incomplete from a scientific point of view, but most active users in a specialized subreddit likely know what they are talking about. It also has the same peer review mechanism like Stack Exchange, and you can always visit users' profiles to evaluate their expertise. Saying a frequent redditor is not necessarily an expert is like saying top users in Academia Stack Exchange are not necessarily academics I think.
So if you can trust (to a certain degree) ideas from TED talks, Wikipedia, or Stack Exchange, then why should Reddit be an exception?
PS: I think the keyword specialized subreddit hasn't been implemented enough in the answers. Yes, all of the points are applicable in a generic subreddit, but I'm talking about subs that the fact one is in there means that they must have a certain level of knowledge, or else they can't never find out the sub. Any random person can create accounts, upvote, and write hilarious comments, but only those who actually have the knowledge can write serious ones and show the holes in my knowledge.
• Are TED presentations academically credible?
• Are there instances where citing Wikipedia is allowed?
• When should we ask questions on Reddit? (quite a misleading title in this context, but anyway)