Reducing the window for eating to 8 hours reduces total caloric intake naturally. I never said it was a "hack". Your linked article explains precisely why intermittent fasting is effective under the heading "The state of ketosis"; when it says "has a similar or even modest benefit over traditional calorie-restriction", that supports what I've been talking about, surely.

And cardio burns calories, sure, but have you tracked your caloric burn when exercising? You can't really do active cardio to burn more than you eat -- not without going into a deficit you have to earn back later. Ketosis isn't as fast as breaking down carbohydrates, so you're right, you don't want to do fasted cardio, usually, unless it's very restricted -- or you load up on carbs via a smoothie or something similar high-availability. I do brisk (~110 bpm average) 30 minute walks during the fasting window early in the morning, but that's about the limit.