Alternatively, I would guess that just generally having free time to spend in any way is a healthy thing. We already know that stress is correlated with worse outcomes. The study does mention that income could be a third causal variable, I think stress is probably a similarly correlated factor.
https://www.gosugamers.net/dota2/news/47182-fly-and-s4-out-o...
Turns out that a healthy body is correlated with reflexes. You need a level of workout activity if you want to be a professional-level video game player.
The "fat and lazy" trope kinda-sorta works for maybe casual games. But a fit body means a fit mind, and a fit mind plays games at a higher level.
This study was looking at Plants vs Zombies: Battle for Neighborville and Animal Crossing: New Horizons players from the general population.
Also note that I didn't claim that gamers were "fat and lazy" as you suggested. I doubt that they exercise at a rate higher than the general population. I would guess they probably exercise at a rate similar to the general population, particularly because so many people play games.
Certain games suck you in and require abnormal amounts of time to feel good about anything. Other games, like Animal Crossing or Plants vs Zombies, are more casual, and have a better life / play balance.
IMO, the "dangerous" games are these grindfests, basically Skinnerbox games (https://en.wikipedia.org/wiki/Operant_conditioning_chamber).
The general population is on average "fat and lazy" and exercise at a rate that is near enough to 0 to make no difference. Age and wealth as factors will outweigh any other input when it comes to these benchmarks.
Different people have them in different amounts and ways. But everyone has these.
Leisure time is not a bad thing, as the title says.
Maybe the gaming landscape has changed a lot, but it would surprise me.
TL;DR - you have time for exercise and sleep. But you sacrifice that time for "fuck about freely to do what I want for once" time.