Back up for a second with the last paragraph there: if the record was mastered for a room sized stereo, it assumes that the room adds its reverb to the sound. W

Back up for a second with the last paragraph there: if the record was mastered for a room sized stereo, it assumes that the room adds its reverb to the sound. With loudspeakers, the room is a distorting filter in the signal path. This and the HRTF distortion are skipped over when listening to headphones/earbuds. So it does make a lot of sense to add these effects to the audio signal in the headphones case. Done right, the headphone playback is indistinguishable from a stereo in a room - mounted to your head, because the spatialized speakers are relative to your head, no matter where you look. So, there is a case to be made for this kind of processing. But I won't trust a random mastering "guru" with unknown credentials to get that right.