I do not think this has anything to do with the argument but I certainly use "pin as app tab".
I keep a large number of tabs open and it is wonderful to have a few of them pinned so I can reach them easily. GMail is actually pinned twice for me: once as an email tab and once as my calendar. Sometimes I pin things only temporarily. For example, I might have eBay pinned for a few days if I am on the hunt for something. Some tabs I only pin at work. For example, I do not use Basecamp much on the weekend but I probably use it a few dozen times a day at work.
The last thing I want to do is spend time hunting for a site I use many times a day a moment or two each time. App tabs are an excellent enhancement to my workflow.