This doesn't seem like a big deal. They use what appears to be a widely supported library for their tray icon, and if you don't want that: "The Dropbox app can

This doesn't seem like a big deal. They use what appears to be a widely supported library for their tray icon, and if you don't want that: "The Dropbox app can also run in headless mode, once you meet the essential system requirements [64 bit, supported filesystem, Glibc 2.27+]. This runs without a graphical user interface. You can install the app, then control Dropbox using the Linux Command Line Interface (CLI)."