I have the Tooltips preference enabled but it doesn’t seem to work (Edge on W10), or not where I expect it to. For example, at the top right, there is an icon with a list with a V on top and a + on the left. I clicked the + and now it shows 14D, 7D, and so on. No tooltips are shown to explain what this button does. I guess it will mark as read all items older than 7 days? It’s just a guess. I’d be afraid to click it to find out it does something else and I have no undo! Or maybe there is a confirmation popup. Anyway, the point is… no tooltips showing to explain the UI.
I agree we could do a better job with labeling buttons that have no text label already. There’s aren’t too many, but there are a few. Tooltips are now used sparingly but they are kind of all over. I have them set to show only on narrow viewports as well, since when the viewport is wide enough, the text label is shown.