Why JSF commandLink in actionListener cant be passed constant in html from variable in code

Its about JSF concepts or architecture, probably i dont understand it.

There are some ways to pass parameters to commandLink actionListener: http://ift.tt/1FqBwXP. But there is no methods to render passing variable in html to pass constant variable from javascript while calling actionListener method.

I see some advantages of using this way like scope independency and lack of need to store variables on server side. What disadvantages of this way? Why its not so frequently used like other?

PS sorry for english, i hope question is clear.