It's true that many apps could be replaced today with a website, specially those that are basically capturing and showing data. But there are still many areas

It's true that many apps could be replaced today with a website, specially those that are basically capturing and showing data. But there are still many areas where native is king. - Games - Audio / Video work - Adobe type of work (photo editing, motion graphics, vectors, etc) - 3d - Office. For me Google docs is enough, but not for heavy users. - Desktop utilities (eg: Alfred, iStatMenus, etc). You could certainly use a web UI for those, and it would probably be fine , but you'd still need some native integration.