As a long, long time user of Reddit, it has been quite saddening to see its descent into the shallow, ultra-toxic husk of a corporate entity that it is today. I'm not surprised by its popularity; it's a headline-surfers paradise, one in which you get feel good points for displays of virtue or shitposting easily digested content in an era of unparalleled narcissism and shortened attention spans. All is not lost though…
I am also a long time reddit user, 10 or so years at this point. It's not obvious to me that reddit is particularly different than it was in the past. There's just more of it now.
I remember the first slide to anarchy was vague titles. "This." or "Good boy" etc would never be upvoted. Instead you would have long descriptive titles that summarized the link.
Images became far more common to share, with imgur and then reddit providing hosting.
Subreddit politics got crazy between moderators of large subreddits and between admins and users when very questionable subreddits started popularizing.
US politics happened. Conspiracies and fake news and then The_Donald somehow taking over half of the entire front page.
I still love using reddit for the smaller communities, but to say it hasn't changed is so false. You can rewind and check out archives of the site from 10 years ago and you'll see.