I have trouble with this. I don’t have any issue with rishonim adding additional meaning to the tefillos, but I have a hard time with the idea that they do not also mean the basic meaning of the words.
I don’t think chazal were trying to trick us when they coined the wording,and I don’t think they were short on wording options. So unless you find an old siddur which begins, “Mikor kol habracha…”, I will be disturbed by the idea that it only means, “you are the source…”.