Because Firefox Add-ons allow more browser-enhancement than Chrome. An example - TileTabs. Not only can you show any number of tabs in a grid like layout one o

Because Firefox Add-ons allow more browser-enhancement than Chrome. An example - TileTabs. Not only can you show any number of tabs in a grid like layout one one screen (so helpful for work), but it can compress them all into just one tab. Chrome's extensions are allowed an icon in one of two places.