Because it's cool. When I first made my Lemmy account, I was looking through my computer's saved images. I had this saved from earlier because it looked so cool. It felt right because federated social media feels like a return to the old web in some ways, prior to the abundance of walled gardens. So a retro logo felt like a cool choice. But it was really just because I saved it when I saw it somewhere so it just happened to be here when I made my account!