The core difference is the YouTube interface uses 3 verticor dots.
Where as the themes on discourse provide a name and the arrows indicating it is a dropdown menu. Now we could modify all themes to reflect this change. Or have behavior dictated by the theme.
3 vertical dots does seem to be used by different interfaces as a popup. Reddit mobile the 3 vertical dots beside profile pic summons a menu from the bottom.
Much like the 3 horizontal bars summons a side panel. Where as the menu we are discussing here in themes uses arrows indicating a drop down.
The core it should be up to the theme author to use a dropdown or the pop up from the bottom.
If we’re going to only mimic behaviors of other sites we might as well come up with a bland theme for all sites regardless of software.
In that regard all menus behaviour should be configurable by the theme author. Themes that were designed with dropdown should maintain behaviour or have a toggle to use new method or original method
The discourse team has often remain stoic on implementing things standard in other platforms like the mutual)true block.
Copying is not a necessity and with idea of configurabikity should be kept in line with customization in the UX.
After all the expression. Just because Larry jumped off the bridge doesn’t mean others should too.