A better answer to this question in reddit is "Does reddit sap the intellectual potencial of humanity?". Imagine if all those people was doing something useful, or myself instead of writing this.
I'm a bit snide here; I object to the "hustle" culture where people are guilted or self-flagellating for having downtime. I've seen too many of my excitable colleagues go too far there and end up with burnout, relationship problems, depression, etc.
Me, I've been chooching along nicely for the past decade and will need to do so for another three decades in all likelihood, and I'm enjoying my downtime (including playing Factorio) while doing so, instead of postponing it until the magical After.
Few of us particularly like how much time we spend on HN/Reddit or go “yeah really glad I’m spending my precious time in this way!” yet we do tend to feel fulfillment from activities like reading a novel or trying to write one or many of the activities we pretend are just the same as playing World or Warcraft and watching Netflix.
And regardless of your personal opinion on the reliability of Wikipedia, I think we can all agree that the ability to quickly find a brief overview of any subject is insanely valuable to society.
On the other hand, I know if I weren't wasting time on HN right now, I wouldn't be doing anything productive.
In my personal experience, reddit/HN has never been the reason I didn't do something useful. The reason was that I just didn't want to do it, and if HN didn't exist I'd just stare at the ceiling.
Do ceilings sap the intellectual potential of humanity?
At least those that already have a drive to know use reddit to sharpen their knowledge. As a research tool itself reddit is pretty invaluable.
So, for me at least, HN provides a fertile place to be productive, but mostly as a place to play around and sharpen my skill.