[ConsiderCrying]

Possibly because nobody who actually reads scientific articles recreationally or for work will read the comments or at least won't consider them a serious discussion. However, leaving the comments off would likely cause those disagreeing to claim it's an "echo chamber" and push them to spread the article with quote tweets about how bad it is, causing much more of a storm. Letting people air their crazy theories is easier than having to deal with them getting built up until your publication is flooded with letters asking to stop whatever perceived malicious agenda you've got.