I'm not some old-timer stuck in the past, suffering from dementia. Well, I am an old-timer, but I've been on computers since the early 1980 Macs, both for work and pleasure. I've worked in computer design with Photoshop for years and with PageMaker and Quark before that, plus a couple of programs designed specifically for newspapers. I've served as an editor, photo editor and published my own magazine. I don't claim to know it all, and I will admit I haven't kept up with that end for the past few years, concentrating mostly on photography, but I still have friends who do it for a living, and every one of them has told me often that "the less one does in PhotoShop the better." The common tendency is to overdo it, and the most frustrating part of their job is correcting all the click and slides others make, even professionals.
Yes, the idea of underexposing comes from Kodachrome days, but I rarely underexpose more -1/3 with digital, bringing it back during PP. I do this most of the time and print at 30X40 with no noise at all. If you think it doesn't make a difference, conduct the test I described. I will add that with the Nikons I shot for decades, one needs to underexpose more than with the Pentax I now use. I don't expect anyone to take my word for anything, because I don't either, especially across the internet. What I suggest is that you conduct your own tests and make up your on minds.
Again, this look is not for everyone. Many prefer the more plastic look of digital, which I think is great for product photography, but not landscapes. Why do some want to expose more detail in the shadows than the human eye notices, or even wants to notice, in a landscape anyway? Shadows in landscapes add drama. That's why we wait for low light angles and avoid shooting at mid-day.