Probably because people treated subs like hashtags, yeah let's repost this photo to as many somewhat relevant subs as possible. Every other social media uses hashtags, so reddit must be the same, right?
But in some smaller, non default, niche communities, you still found plenty of quality, original content. Many of those were too small to probably even make it to Lemmy at all, let alone gain some traction. But I'm happy /c/flashlight is over here already.