There are, of course, many people with memories of 4chan that precede that of mine (oldf*) - I could only even articulate what I was seeing on 4chan at the age I was around 2014. But by 2015 - with only 1-2 years of experience on the site - I noticed a drastic downturn of the authenticity in posts and comments that I was used to. Then, I saw quality of topics and speaking points go down in 2020. And finally, I saw the social fabric of 4chan itself go down essentially right after Omegle was shut down. By mid-2024, I couldn't even trust it for contrarian or less-conventional (or, frankly, brutally honest) viewpoints of topics they purported to care about.
And honestly, as things got better in my life and I went out to be more recreational, I went from going on 4chan once a day - to once a week - to once a month - and finally, to only when I wanted to see edgy takes on divisive current events.
I'll miss all that, despite all it lost over the years. And I'll miss the element of design and mannerisms in its userbase. It required an upfront investment to even understand how to engage with, and a "lurk moar" attitude. RIP.
Edit: It was also very crazy watching small groups of people turn insider-jargon into mainstream terminology. I'll also never forget watching the thread of QAnon's conception in real-time. Crazy stuff originated there - both in substance and meaning.