"I think the reason people started calling it the “system tray” is that on Win95 there was a program called “systray.exe” that displayed some icons in the notification area: volume control, PCMCIA (as it was then called) status, battery meter. If you killed systray.exe, you lost those notification icons. So people thought, “Ah, systray must be the component that manages those icons, and I bet its name is ‘system tray’.” Thus began the misconception that we have been trying to eradicate for over eight years…"

Doesn't change the feature was already there, with Win32 APIs to interact with it.

Yeah, but until Windows 11 it was the notification area! But for Windows 11 it looks like they gave up on this fight, finally, and the general UI in Windows 11 actually now calls it the system tray. So presumably that is now its official name.