I noticed this a while ago. After thinking on it overnight (saw the post linked in #price yesterday) here's what I think.

1. Many users took a step back and stopped engaging or just quit over the last 12 months. Used to be able to post and get a lot of thoughtful comments by people who actually read the post. Now, they're all gone. There's still the odd user here and there but the guys who started in summer 2016 or thereabouts when the initial surge came, many are gone or appear gone.
2. Users divided themselves into various Discords and otherwise circlejerks and only interact with their group, typically one where they all pay in for a bot to "curate" them.
3. Most of the replies users are seeing are either bot replies or copy paste replies. Good post dear. No one really gives a shit about the post itself. It can be a post in gibberish and with a picture of a turd and they'll still get a good post dear if they've got some SP and there's a chance they'll upvote the comment.
4. Those not paying for vote bots are getting left behind. Their work isn't as highly valued since the payouts are smaller. Small payouts = shit. That's how people see it. Take @runridefly for example. He blogs about his kids and random things he sees and pretty much has done the same thing for as long as I can remember. He's getting $3 a post in organic votes. To a new user or pretty much any user who joined over the last year that's an indication that it's crap and not worth a vote. Cause you know, no Trending. And Trending = God.
5. Some, like @ramengirl, lost their benefactors. And the rest of the community just doesn't value or overvalue them all that much. Turned out their posts weren't made of gold after all.
6. Old users didn't take the hint and start networking on Discord. There's 100+ Steem Discords now. I know because I'm at the max limit and that's because, in part, when I launched my Witness someone came to me and said "you're not visible enough, you need to be accessible". Not in those exact words but generally. Problem with this is it directly fucks up content creation -- Discords take up a lot of time and content creation takes up a lot of time and often you lose quality.
7. Everything is about minnows. Minnow this and that and a new user must deserve everything because they're new and they deserve the world because of their newness. The Trending page, bot owners, whales well they all deserve the world because they're investors in whichever way. There's a lot of deserving going on. Dolphins and older users, those guys with rep 65-71 typically, they don't deserve shit. They're that middle class and should go fend for themselves.

I'll edit the comment if I think of a few more.