Note that Arc had no or minimal AI when it launched; its appeal for so many of us was its refreshing opinionated stance on the browser UX. The AI hype train hit them hard and they tried to pivot to Dia, which leaned fully into AI but did none of the fancy UX things that Arc did. From what I could see online most of the fans they attracted with Arc were turned off by the pivot. It was peak early AI hype, which didn’t help: so much more smoke and so much less fire than there is now.

Dia now does appear now to have many of the Arc UX features. Plus AI.