>>4122466She's dumb as shit, because she's a specialist.
Anyone can become an uncreative mop of averageness by attempting to learn math, and do memory-intensive tasks to make up for the lack of talent.
Gura is genius and original enough to understand she would amount to nothing if she worked on her math. So instead of covering her faults, she accepts them plainly, and specialises on her talents to the max, which gives her an edge over others.
This gives her an incredible sense-of-self and humility that is what people love most about her, as well as showcasing her actual talents and presenting yourself as a confident and complete, instead of anxious, insecure and unmotivated by failure.
That's genius, anyway you put it.