You’re only getting a notification if the program is running 24/7. You seem to be contradicting yourself here. The purpose of a tray icon is to provide a hook into a running background service which can provide notifications, status, and pop up a display if needed, without rendering a full window at all times. Mac accomplishes the same concept with both tray icons and their dock, but it isn’t actually any different. Linux has plenty of things with tray icons which implement this concept, thunderbird does not. Your distaste for email is not really relevant so I’m going to skip past that – I still want to get emails when they arrive, and for that to happen there needs to be a service running. Thunderbird for windows meets the above requirements, thunderbird for Linux does not, it’s simple as that. I was using this as an illustration agreeing with your claims that the philosophy is different between the OSs. On Mac, everything is a service and windows are optional. On Linux and windows it’s more of a choice that each program makes, but on Linux it does lean towards fewer background tasks. Including, in this case, getting email notifications.

I can easily get to 10G in a browser alone thanks to their philosophy of burning through ram.