"But 'radio' is not a monolith! There's no 'radio' guiding everything! Radio is a collection of many stations, not a single thing!"
Someone on this board said something like that to me whenever I suggested that the radio business as a whole has failed to respond effectively to the challenges presented by streaming, and is doing just fine, thank you very much.
But anyway, I'm not surprised. Fallon never really filled the shoes of his predecessors, nor did he rise to the level of "screw you guys, I'm making my own show" like Letterman or Conan, and didn't reinvent/deconstruct the genre like Craig Ferguson. In order for "late night" to compete, it has to move beyond the formula of "host delivers monologue, does a bit or two, then sits down with celebrities promoting their new movie/show" formula.