Ask HN: Why do browsers have to be refreshed periodically?

If you mean pages, then you refresh to get new or updated content.

The update/refresh process can be automated but adds complexity. This might be worth it in a a dynamic multi-user application or for a feed of information but adds no value in most cases.

The 'update' button in the top right corner changes green to yellow to red.

Yes, so open tabs could be stale. But is there any other reason for browser refreshing?