This has not been my experience. Claude artifacts at first, then Claude Design after it was released, are excellent at design! The way I can steer the model updating the design with different ideas and visions, even adopting different design systems like Material 3 or Apple’s HIG it has been phenomenal.
It's also by far the best in my experience at a request like "it's 3:55 and I need a few slides on the topic of the Gettysburg Address for a 4PM meeting."
I wish it was more integrated into PowerPoint but it's still the best slide generator I've used.