Having followed the link and had a bit of a read now, I do wonder a bit about the quality of the tellys people are watching it on maybe - some modern flat screeners do not do sound well.
Yes, that point was raised in the radio discussion this morning.
Programme makers should be auditioning their final mix on a crap telly thobut. Problem presumably is that either they don't bother, or they've been working on the material for ages and could recite half the dialogue from memory by the time they get to that point. (And selection bias, in that people mixing audio for a living probably have above average listening ability.)
Plus you've got to balance the artistic aims of realistic diction, background music and certain types of microphone technique
[1] versus the SNR requirements of the significant minority of the population who have some sort of hearing loss but prefer to complain about mumbling rather than use better audio kit or turn the subtitles on.
[1] I find the up-close-and-personal microphone approach common in USAnian television drama can be quite distracting at times.