So what? Like if something was posted years before should it never be posted ever again? We are talking 5 years here, and the information hasn’t become deprecated or outdated

Not at all! As the other commenters have pointed out, no criticism is implied. Reposts are fine after a year or so. This is in the FAQ: https://news.ycombinator.com/newsfaq.html.

It's just that readers are often curious to look at past discussions. Sometimes I point that out: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que....

I do not believe that is dang's point. He often posts comments like these under recurring posts, I assume in hope that the past discussions could also be of interest to the readers.

People might be interested to see what was said last time.

Its very normal on HN to point to earlier discussions on the same article or subject and is normally intended as help rather than a complaint.

What a guy, to criticise dang himself. :P

In case it isn't clear from the responses, dang is the HN moderator. He regularly groups related stories and references past threads.