When you run an app from the taskbar or start menu, you single-click on the app icon, or single-click on the Start menu button and then single-click on the app.

Sure, icons on the desktop, or just about anything in a file/app explorer window, require a double-click by default, because the lineage of the main desktop area is just a file explorer window without the window decorations.

I think it might be about stakeholders wanting the web to "feel" more native and interactive. Double-clicking to "go" feels too much like you're interacting with the web as if it's a file browser. They want it to feel more immediate?

In principle I'd prefer the consistency of double-click or double-tap everywhere, but I'm used to adjusting based on context. Wouldn't double-tapping annoy everyone who primarily uses mobile devices?