Lua dabbler, mainly. Or translator. It depends.
You won’t believe how many sites break down when you use just Wacom pens, mousekeys, or portrait monitors (e.g., Vector 2022 breaks down with portrait monitors). You don’t even need to talk about screen readers.
If you have a timeout and the user can’t complete a task when using mousekeys (an accessibility feature built right into MacOSX and X11), your timeout is way too short.
If you set up your monitor to portrait orientation (very common for professional edtiors) and your layout breaks down or your main text area suddenly becomes narrower than a newspaper column, you CSS failed.
If you use a Ducky keyboard (hardware mouse emulation) and you can’t get the mouse cursor to hover above any UI element, your “click targets” are way too small — for desktop — and we aren’t even talking about an accessibility device here, this is a piece of mainstream gaming gear.