I recently read this article which suggests that it's impossible to make caffeine free chocolate. Why would this be the case? If we can make caffeine free teas and coffees why can't we strip the caffeine out of chocolate too?
When taken literally, the article you cite is simply wrong. See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5302282/ -that's scientific proof that decaffeinated cocoa does exist. I have no idea if someone is actually making chocolate bars out of it, but there seems to be no theoretical hurdle for it. There is some remote possibility that the decaffeination may change the physical qualities of the cocoa powder, or that it is not well suited to other cocoa intermediate products such as cocoa butter, which could make producing a decaffeintated chocolate bar challenging - but even if that's the case, I would expect professional food technologists to be able to work around that.
I won't speculate on why the site supplied incorrect information. My personal opinion is that I don't trust sites that feel comfortable making broad health claims, and the site you cite is very much focused on doing exactly that.