It is a subconscious level ad for the utility/value of the platform. You don’t need to be overt about the screenshot containing Lemmy by name. Any subtle details are all that is needed. This is all it takes to attract the most valuable people; simply show them that they are missing out on something useful. It is effective psy ops.
But what if we like it better this way?
Aside from one or two people that frequently posted in niche subs, and the legends like Sprog, everyone on Reddit felt like a stranger I was meeting for the first time.
Sure, more posts are nice, but in exchange for an endless supply of bullshit to occupy my brain, I’m seeing posts and comments from people I recognize and remember and I feel more “at home” and less like a visiting consumer.
There is always a turn over rate. Without an advertising mechanism, it is a slow death.