Anthropic switched to HTML artifacts because they cut output costs by 8 cents...

https://www.slideserve.com/aaron_ward92/what-s-a-practical-html-artifact-layout-for-a-code-review-with-3-findings

Anthropic switched to HTML artifacts because they cut output costs by 8 cents per file and handle 4.4 million views with less lag. HTML lets their teams build clearer design docs, smoother code reviews, and richer reports compared to Markdown