I suggest expanding your imagination skills. There are definitely worse activities, like watching TV.
And there's physical limit to how much physical activity one can be doing. There's definitely a point of diminishing returns there.
And the skills one can develop with carefully curated games are hard to reproduce in any entertaining manner.
I mean, sure, I could have him do math but it's a lot more boring.
Playing games is definitely an "and", not an "exclusive or" proposition.
I was given access to computer games at that age and I'm definitely appreciative for it. I only realized the value when I was well into my 30s.