System76 is no stranger to desktop development nor Rust-lang. Their team is relatively large, skilled, diverse, and highly dedicated, with years of experience in high-level and low-level development, UX/UI design, and even an OS built from scratch (Redox OS), and so on. Unlike elementary OS's Pantheon, which builds upon existing frameworks like GTK & forked Gnome components, Cosmic (Epoch) is entirely written from scratch, toolkits and all. System76's approach is also more comprehensive and ambitious compared to elementary OS. They're developing native Rust applications like the COSMIC app store, terminal, screenshot tool, and text editor. Early performance tests show promising results, even in virtual environments. The company's financial resources also allow for significant investment in COSMIC's development, supporting a dedicated team and a long-term vision. This contrasts with elementary OS's more gradual, community-driven growth.
Pop_OS! is also an already very popular distribution, and importantly popular amongst newbies. System76 is also a hardware vendor meaning they can tightly integrate Cosmic with their hardware, and in fact do so much more easily than what they've already been doing with Pop_OS!.
Compared to ElementaryOS, System76 is in a much better position.