He doesn't have any problems.
He listed blown highlights and noise in shadows.
There is no down side to using the full capacity of a sensor.
No one argued there was a downside, what was argued is that sometimes the sensor doesn't have enough DR to record the contrast in the scene and you have to choose what to portray accurately. Sometimes it's the high end, sometimes it's the shadows. I have no idea why you put words in my mouth and the ask me why I said things I didn't say.
If you don't use the full capacity of the sensor you get lower SNR and DR with no benefit. So why do that?
I have no idea, that's why I don't recommend it. What benefit do you get if your sensor DR doesn't capture the full DR of a contrasty scene using a dogmatic approach always exposing the right, is the always best choice?
In the deepest shadows base ISO is not noise free and if you intend to lift those shadows then more exposure is a real benefit.
Exxposing for the shadows increases exposure. You let more light in, because you are exposing for a darker part of the image, eliminating noise. Some times the object is not to lift the shadows, the object is to expose so the shadows don't need to be lifted, because they are within a stop of normal exposure.
However good noise filtering software is, it all takes an edge off and if you can avoid using it you keep that edge and better IQ.
Better resolution measured in lw/ph is not automatically better IQ. AI noise reduction often improves IQ, while reducing noise, if you conseider IQ to be the emotional impact of the image. No oe has ever proved that technical specs determine IQ or even have any relationship to it. That is camera company gibberish. A few years ago, a person won a voted on Flickr prize for best in class , with a 12 MP K-x. A kit worth under $500. Thousands of people who spent more and had technically higher specs, lost to him. What that tells me is technical IQ is not the same as artistic IQ, and when people judge photos, only artistic IQ counts. Thousands voted for an image, over much technically higher spec images.
I remmeber being at a craft sale with my wife, at that time we still had a few K20D images for sale. A customer selected one of my K20D images, poor shadow detail, brutal by my current standards. At the time she was shooting a K-5. SO she went into the whole explanation about resolution, better handling of noise, more true colours, etc. "We have much better images." He put his hand up to stop her and said. "I want that one, are you going to sell it to me?" He asked us to pick them up from the framing store and hang them for him. (My wife sold him one as well, they were priced at $300 each, we gave him the two for $500.) He had a cathedral ceiling in his kitchen , a whole wall covered in photography, at least 30x12 feet. There was my technically inferior 14 MP APS-c image up there looking not at all out of place with maybe 15 other photos taken with Canons and Nikons, probably full frame images. The lesson in that?. Technical specs do not reflect superior IQ. IQ is determined by how other humans respond to the image.
Here I've given you two examples of how wrong it is to worship technical excellence in an artistic medium. You just never know what people might like. I'd suggest in many cases that while possibly reducing resolution a bit, AI noise reduction software produces more artistic images (as in enjoyable by humans.) to the point I sometimes use it on images that don't have much noise. It increases the artistic IQ, which for most human beings is all that matters. But, I do know a few photographers for whom their technically analytic mind stops them from appreciating the artistic nature of a photograph. If it's not 10,000 pixels by 6000 pixels, with no noise, purple fringing or CA, it's automatically not good enough. Bias strikes quickly in those types, and prevents them from enjoying the 95% of the excellent work of artists, because they aren't artists, they are technicians. Yet I've seen ,many photos published that had both purple fringing and CA. That's why techincains don't curate art shows. Many are incapable of seeing the artistic value of less than technically perfect images. And many of the images they prefer, are of no value to the artistic human.