No, LLMs just can't do math.
It's like saying that people can't turn high torque nuts on machine bolts, because you can't use your fingers to do it. But you can use a wrench, so effectively, we can turn high torque nuts on machine bolts even though it isn't something we can natively do unaided.
I asked Opus 4.8 "What is 12 times 13" and it gave me "156".
So it would appear that your statement is no longer true.