Tabs = Windows

Have you ever wanted to look at two tabs in your browser at the same time? As far as I know, FireFox doesn't have any function to "detach" tabs.

If you could detach, resize and reposition browser tabs, they would mimic the function of desktop windows. You could have a "virtual desktop" of sorts running in your browser.

Being able to use tabs as windows would further the dependence of the user experience on any specific OS. I wonder if this is why Microsoft was the last to enable tabbed browsing.

Employment vs. Business ownership.

Upon consideration, in general, employment is the best option for someone who specializes in a specific field. On the other hand, running a business is best suited for somebody who has many varied skills.