Supposedly it’s an SEO thing. The theory is that Google is biased towards novelty and so penalises older articles (although I’m not sure how removing the date would help because surely Google would still know how long the article has been online for.)
I have no idea how true that is but I remember hearing SEO folks talk about it a few years back.
Some content mills seem to display a date but automatically update it periodically. Sometimes you can outright see it can't be correct since the information is woefully out of date or you can check from Internet Archive that the content is the same as before but with a bumped date.
I have no idea how true that is but I remember hearing SEO folks talk about it a few years back.