Figma's biggest strength is in UI design. Open illustration, while possible is not so great. (I still love Illustrator for this purpose, others may disagree or have other favorite tools). Figma allows UX/UI designers to speak a congruent language with UI developers. A design system or component library can be mutually understood. Things like, "we're using our 80% gray button here" can be very easily communicated. That's not at all impossible in other tools, Figma just takes it to a very nice level.
