Seems like a LogSeq/Roam/Obsidian alternative?

For sure. The idea here (or at least how I've been using it) is to use Atomic as catchall place to put personal notes, interesting articles, research ideas .. pretty much anything, and Atomic will handle the categorization and knowledge synthesis. For example, I have a knowledge base that uses RSS to sync top Hacker News articles and I'll occasionally generate new wiki-style articles which summarize and synthesize the articles based on top-level categories (AI, hardware, philosophy, you name it).