Minor quibble, I’m pro-tone control and pro-loudness.
IMHO the issue that is ignored in the video is that graphic EQ’s and many built-in tone controls were not that great. Even flat, engaging/disengaging the controls often would result in noticeable degradation. No wonder, the circuits used to implement the tone controls were often 3rd rate compared to the rest.
Luxman is one company that consistently has excellent and transparent tone controls. I'm not an expert but I believe in their modern tube pre's they use extra tubes just for these circuits.