that Bg4? line is just a blunder, it gets crushed every time..
but youre right, do to the philidors passiveness in most lines the score isnt that good. blacks goal is to equalize before doing anything else, which might be why its not super popular anymore. when its done at a higher level they start with a different move order
I am wondering what are the stratagies with the phlidor, most players I faced who used it I have crused and most lines in databases have a 70% or higher win rate for white.
I have one example of a game played, it is in the diagram attached.