I've found that in general almost all popular health journalism/news coverage is awful. You're much better reading primary sources (particular, recent reviews in peer-reviewed medical literature) to get much more readable and information-dense, and useful resource (as well as a list of citations for followup and verification). I'd recommend anyone interested in any health topic to simply search for "pubmed [topic] [keyword]" to get any substantive information.
For example, a search for "pubmed walking versus hiit" actually turns up the answer to exactly what you were looking for.
To save everyone interested a few clicks: "In conclusion, in this population of relatively untrained but healthy young adults, our results suggest no particular advantage for very high intensity training models" [0]
One of the things to keep in mind is that any one study is part of a larger picture and part of why I recommend people do their own searches so they can see what kind of studies are out there (or to start with reviews). For any individual study you have to at the minimum pay attention to sample size/population, what kind of study it was, and often looking at the methods/study design as well. There will often be caveats or additional wrinkles. For example:
Shiroma, Eric J., Howard D. Sesso, M. V. Moorthy, Julie E. Buring, and I‐Min Lee. “Do Moderate‐Intensity and Vigorous‐Intensity Physical Activities Reduce Mortality Rates to the Same Extent?” Journal of the American Heart Association 3, no. 5 (September 16, 2014). https://doi.org/10.1161/JAHA.114.000802.
"Among men, but not women, additional modest reductions in all-cause mortality rates are associated with a greater proportion of moderate- to vigorous-intensity physical activity performed at a vigorous intensity."
Fisher, Gordon, Andrew W. Brown, Michelle M. Bohan Brown, Amy Alcorn, Corey Noles, Leah Winwood, Holly Resuehr, Brandon George, Madeline M. Jeansonne, and David B. Allison. “High Intensity Interval- vs Moderate Intensity- Training for Improving Cardiometabolic Health in Overweight or Obese Males: A Randomized Controlled Trial.” PLoS ONE 10, no. 10 (October 21, 2015). https://doi.org/10.1371/journal.pone.0138853.
"While both exercise groups led to similar improvements for most cardiometabolic risk factors assessed, MIT led to a greater improvement in overall cardiovascular fitness."
I'd also say that while it's tempting to just skim through the abstract and the conclusion, oftentimes, the Discussion is where the real meat is, and in cases of controversy, careful attention needs to be paid to the authors, the raw data (sadly, especially in the nutrition space, there is often discordance between the observations published, statistical massaging, and the conclusions drawn...) and followup commentary.
For the HIIT study you referenced, I did find this commentary, which was pretty interesting (it's worth noting that I don't consider this topic area to be particularly controversial/heated - differences seem modest, and honestly, the biggest thing seems to actually be getting any physical activity, vs none for most people...):
Coswig, Victor S., Paulo Gentil, João P. A. Naves, Ricardo B. Viana, Charles Bartel, and Fabrício B. Del Vecchio. “Commentary: The Effects of High Intensity Interval Training vs Steady State Training on Aerobic and Anaerobic Capacity.” Frontiers in Physiology 7 (October 25, 2016). https://doi.org/10.3389/fphys.2016.00495.
That's true. When reading the Discussion of the article I quoted from, it struck me how much they talked about the aspect of enjoyment. But when you think of it, this aspect is huge, because it basically determines whether people will actually follow through or not. A few percent increase in VO₂max is useless if people will hate the regime and will simply not do it.
For example, a search for "pubmed walking versus hiit" actually turns up the answer to exactly what you were looking for.