Genuinely curious, does playing video games really improve focus etc.? Is this anecdotal, or did you read some paper somewhere?
I find games that require lots of exploring, solving puzzles helps improve my focus. In most FPS games, this only works if you strategize your approach in gaming. E.g considering the next X moves ahead, scoping vantage points etc.
Also, when I just need to clear my head, I personally find that there's nothing like games (besides exercise).
Fun anecdote, when I met my SO, she was in incredibly into exercise and I was not. But I was very much into games. We ended up influencing each other. Now we game & exercise together..
I think overall it's a net positive if done in moderation.
If the game is challenging for you, it will likely help.
Check out neuroscience books if you want to be deep in this stuff.
The theory is controversial. The effect likely isn't too big, or it would be harder to design experiments where it doesn't show up at all.
But even assuming the theory is correct, playing video games wouldn't be considered beneficial, at least as long as you are enjoying it.
This should be somewhat obvious: if you enjoy doing something you are obviously not training your capability to do something that you don't enjoy.
The closest you can get to have license to indulge is that Baumeister would predict not playing video games (when you would like to do so) will deplete your willpower, and make it harder to resist other urges (such as not working) for that day. Over the longer term (several weeks) however, repeatedly resisting that urge to play would train your willpower.