It tends to cycle, just like many relationships. The flush of novelty is exciting; it contrasts positively with what's available elsewhere. Then you notice the annoying things, then the dismaying ones. Eventually that too becomes background, which other positive-again things can stand out from. At some point you realize it has all been there all along, if in fluctuating proportions.
It's affected by macro trends (https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...) and the swings going on in the world at large. It's affected by what's going on in a person's own life. Perhaps most of all, it's affected by the impact of the most recent things you happened to see that made an impression. There is a strong component of randomness in the latter.
People in an 'up' cycle with HN don't tend to make posts about it, so posts like this—through no fault of any one poster—are dominated by the 'down' cycle. There is a long tradition of these, going back about as far as HN itself. It produces a paradoxical "things have always been getting worse" sensation if you zoom back far enough.