This has been said by every long term user of these sites. And not at the same time. It was always better in the past. It's probably partly true... yeah, quality can decrease as things get better. But it's also partly an illusion of aging in a changing world. Ten years is long enough to completely change the way we write and express ourselves.

It's actually sort of in the Hacker News Guidelines (https://news.ycombinator.com/newsguidelines.html):

"Please don't post comments saying that HN is turning into Reddit. It's a semi-noob illusion, as old as the hills."

Luckily I am not a LLM and can read and select things rather fast without processing the crap. Both HN and some subreddits still are fine for quality if you know the users and their reputations; just skip the rest. Worse than 10 years ago, still a lot better than mostly anywhere else.

you need to expend resources (e.g. "proof of work") to post, to drive away low effort spam. https://stacker.news/ is an interesting experiment in that regard.

And yet the comments still provide more value than the article, almost always.