to me the main feature that makes arc browser appealing is how they combine the features of open tabs and bookmarks into one intuitive system, and making switching an open tab into a tab in the saved section really frictionless, and allowing you to view a tab in the same section in the same manner as an open tab. It also then automatically takes care of the memory management aspect of closing unused tabs for you while keeping the visual representation of open/saved tabs the same, and letting you be confident that the state of the saved tabs section is persisted.

No browser that I've seen comparing itself to arc really does this. I downloaded zen and looked at it for like 30 seconds and it doesn't look like it does this either.