It definitely was a few years ago, when it was about memes and anime and before it went alt-right/Trump.
Useful when you want to get a sneak peak at the propaganda campaigns, and internet brigade tactics and talking points that are about to be rolled out against the public (or A/B test some of your own), but not so much for serious debate.
Like 99% of the stuff you see on there is going to be deceptively worded or presented, or just factually incorrect. If you're letting 4chan influence your opinion, you're using it wrong.