I believe that this is a reference to one of the guidelines: "If your account is less than a year old, please don't submit comments saying that HN is turning into Reddit. (It's a common semi-noob illusion.)"

It's not a very good way to reference it, though, and in general comes off as snobbish. There's also a distinction between complaining that HN is going downhill (which the guideline discourages) and asking how to prevent it from going downhill (which I see as a good topic of discussion). Of course, asking what HN is doing to prevent it is one which might be more easily answered by watching the site for a while.

Based on an extremely unscientific sampling (going back a bit over a million items and then hopping around randomly between 300 and 386 days in the past), while there is a slight decrease in the level of conversation - and a fair amount of karma inflation - it's not too noticeable, and I expect that it would be somewhat difficult to distinguish between a discussion thread now and one from a year ago, if all temporal identification was stripped out. Maybe the type of articles has changed a bit, and maybe really short comments tend to be upvoted a bit more than they used to, but by and large HN is not going downhill.

I'm not specifically referring to Hacker News. I'm building something that has a large community aspect to it and I wanted to know so I can avoid a potential "Eternal September" later.