I think the point is that diversions don't really require much concentration, they're easy to consume. If they did require a lot of concentration they wouldn't

I think the point is that diversions don't really require much concentration, they're easy to consume. If they did require a lot of concentration they wouldn't (usually) be diversions. Depending on the goals you've laid out in front of you for the day, Chess is either a diversion or the "right thing". The "right thing" is up to you. Considering the investment Chess requires I don't think it's typically what is pulling people away from tasks they should be doing.