I think both can be true. While what you say feels holistic and true philosophically, in day to day, we cannot control for 1000 different variables and some things have more of an outsized effect than others.

For example if someone wrote "Is Exercise the key to a healthy brain", it sure can look click-baity, but in practice it's a tried and tested lever to improve brain health. Sure, you can say "oh there are 10,000 other things that influence brain health and it's a very complex inter-connected system", but you miss the fact that not all of those 10,000 things are equally deserving of your time or even under your influence. In fact, things like exercise or meditation can fall under the "weird trick" category.

If focusing on mitochondria's health falls under that "outsized effect" category is the thesis of the article and remains to be seen if it can be included in the same category as other tried and true influential levers.