Walking is recommended as exercise for fat people. It is low impact and sustainable. Fat people can do it without getting injured. They often can't run. It is not an efficient form of exercise (it takes 2+ times as long to walk 10K as to run them) and it doesn't get the heart rate elevated.
It's much better than nothing, and anyone trying to be seriously fit ought to walk or bike everywhere and never get in a car. Walked kms are kms too. But it's not running.
I went through a period where I didn't exercise except for the walking in my daily life (I don't use a car, so this was normally about 10k). It kept me from getting fat rapidly, but certainly didn't keep me fit. Far better than nothing, and far less than exercising.
One has to contextualize what one reads. First, the "experts" aren't. Sports scientists/doctors in general are mostly quacks and incompetents. The people quoted in newspapers are likely to be publicity hounds, which is a contraindicator to quality. Second, most of what is in the media is directed to the average population, which is mostly fat and doesn't want to work hard.