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

https://www.mikegingerich.com/blog/anthropic-adopts-html-over-markdown-for-workflows/

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