No, but past recommendations for older adults (note that the average age in the study was 72 years old) were towards "gentle" or moderate exercise. We're seeing a shift now towards recommending real weight lifting and higher intensity as we age. ("Real" -> closer to powerlifting in terms of goals and methods)

There was plenty of obvious, common sense assumptions that didn't hold at all when methodically tested, like sugar rush in children. And this specific type of studies tries to find a sweet spot between benefits and effort taken. Some results were unexpected, If I recall correctly on found that having to take three flights of stairs daily outperformed many exercise regimes designed for elderly.

I have met people who figured, because they don't excercise they don't wear their body out, so their joints etc. will last longer. Same for injury, no sport no injury, that must be good!

That wasn't what this study was investigating.

Well I guess reading the article could ease your confusion. Unsurprisingly it is a bit less generalized than your take.

Sports and exercise are definitely beneficial, but any sort of activity presents a risk of injury.

If people work out, or play sports, without knowing proper form, without using protection or precautions, they'll get injured and then worse off than before. Realistically, manual laborers should be in real good shape, but often their jobs are so low-wage, and they're so interchangeable, that safety precautions are ignored and must be regulated/enforced.

I took up roller skating and was rewarded with a broken leg. I took up gym exercise and was repaid with a hernia. Both required surgery. No regrets! Only wished I could've better understood how to exercise safely!

I once encountered a FB group that was for people to discuss "sports injuries sustained while we were in bed" and I could totally relate, having done weird stuff to my shoulder overnight, rather than pitching a baseball game...