Feels like a lot of them are using Bootstrap, curated Tailwind elements or Wordpress templates. In which case the challenge Anthropic faces is convincing them the extra flexibility and magical "type into prompt" approach to customization of Claude Design is worth the compute cost...

Figma is answering a different question which is "are you prepared to spend time and money on full time designers to have pixel perfect layouts agreed with managers and consistent across platforms" and non-AI tooling has been orders of magnitude faster and cheaper at generating something that looks good enough as end results rather than mockups since before it existed.