"BTW, why would anyone add back/fore buttons on his page if every user see them both on the browsers toolbar? "


For client specific needs. For example web based online training manuals or Operation and Maintenance manuals. Folks on production floor can be really unsaavy with browser navigation. Also may depend upon how Browser is configured at different workstations on the floor.

You'd be surprised at some of the guidelines set by clients, especially those will low budgets for training their employees.