I agree. Rule of thumb: imagine that every hour spent making pretty pictures with Figma is a week's worth of development time. Then people won't feel so great about all that time spent on "UI/UX" before the coders even start work!
They can even use 0.5, 0.3, or 0.7 mechanical pencils, or any other size. For paper options, they can refer to a previous HN discussion [1]. The WYSIWYG functionality is almost perfect, though.