Not sure what I'm rambling on about here, but I took the time to write it so I might as well post it.
I assume many of you, like me, are on Lemmy because you fled Reddit for one reason or another. For me the API fiasco opened the door, and me realizing I was addicted to it made me leave.
I enjoy conworlding, both my own and that of others, differently than I do more polished works. It's raw unfiltered imagination. Sometimes the ideas are stupid or cringy or poorly presented (I know mine are at least), but they have an authenticity that you don't see in published works, and I think there's a joy in the very act of pretending, or, to dignify it with Tolkien's words, sub-creation.
The size of /r/worldbuilding meant there was always something interesting to see or read about, whereas other communities are less active. There were problems though. Art posts were disproportionately favored, a consequence of humanity being an overwhelmingly visual species, in my opinion. This left those of us without artistic talent feeling ignored. The mods could be trigger-happy about posts that they felt didn't provide enough context. I posted an image that I thought was adequately explained in the title, but got a warning from the mods because I didn't write a novel's worth of backstory. More "gamey" prompts were deleted. I once posted a "worldbuilding mad-libs" game where you had to fill in the blanks in a way that made sense in your setting, but it got deleted pretty quickly.
Besides the mods, there were a glut of posts asking about characters and characterization, which isn't really worldbuilding, as well as comments complaining about stuff that is worldbuilding, like realistic map making.
In a way I signed up for this. I've been trying to de-urbanize my online activity, separating myself from the massive centralized platforms that dominate the modern web and seeking out more niche corners of the internet to fill my needs. I guess I shouldn't complain about it in that case. Of course this community is going to be less active. It's smaller than Reddit, and that's what I wanted.
So. On the one hand, it's valid and perfectly alright to lament the fact that there were good parts of a reddit community that you miss. That's perfectly normal. Reddit wasn't all bad.
But on the other hand, it's important to recognize that some of the downsides you mentioned are going to be a problem in any community large enough to reach such critical mass.
Someone else here mentioned that Lemmy will likely get there in the end. But the problems with that community on reddit are kind of endemic to communities as a whole. So you have to decide how much good is worth taking the bad.
On the third hand, I also miss some communities on reddit, and I think everyone who's left does to some extent. I am happy that people feel comfortable enough here to really really about what they miss and even to commiserate as we reminisce a little bit. It's this kind of thing that gets people talking and sharing ideas.