Ask Lemmy

Like I say in the OP, Lemmy and other Redditlikes have a default post sorting algorithm that prioritizes new posts over old but still active posts. This has a huge impact on the culture of the site. Topics are more ephemeral. Once they drop off the first page nobody will ever see them again.

On a forum, if a person wants to make frequent updates over a long period of time on a single topic, they can make a single megathread that stays visible as long as new replies keep coming. On Lemmy et al. the topic quickly drops off the radar no matter how many people reply, meaning if the OP wants to make frequent updates on a similar topic they have to keep making new posts if they expect people to reply.

Let's say I'm on a car enthusiast forum, for example (IDK anything about cars). And let's say I'm restoring an old car and want to share my progress over the course of months. I can make a single topic about my project and post replies to it with pics and updates about what's going on. As long as I keep updating or as long as people keep commenting on what's already there the topic remains relevant and more importantly visible, and could remain so for years or even decades.

Now let's imagine the same project on a Redditlike site like Lemmy. Yes I can do the same thing as above, make a single post and keep replying to it, and people can chime in with comments. But because the default sorting algorithm causes older posts, no matter how active, to drop off over time, I'll be replying to the void since nobody will see the post. In order to maintain the same level of visibility and interaction, I have to make new posts for each update. It's less likely that my project will become an enduring part of the community's history because it will either get swept away by new content if I use a single topic, or be scattered across several disparate posts.

Other differentiating factors that people have brought up are signatures and avatars. Avatars are really small on these sites and there are no sigs at all. These were modes of self-differentiation on forums, allowing individual users to be more recognizable and allowing connections between users to develop. On Redditlike sites you're just a username and maybe a little icon, making it harder to see anything but disembodied ideas floating in the ether.

Yes I can make Lemmy behave like a forum by sorting posts by latest comment and using the "chat" display option for comments, but nobody else does that so posts will get swept away by new ones for them even if they aren't for me, meaning the culture never grows around this system.

It's not what I would consider a forum. Traditionally forums were built around an interest or topic, Lemmy like Reddit is a conglomerate of communities or subreddits some of which I'd consider forums. Lemmy doesn't have the population to support nitch groups like Reddit does.