Well Chess Is considered as a sport, Some the greatest as too took a diet too keep the weigth and energie at most during tournement. At some lvl the focuse and the concentration you most have the play is so high that you could loos weitgh.

Starcratf in some way as the same pattern, you have to think a head of the other.

What's the difference between being very good at Star Craft 2 and being really good at throwing a ball?

1 requires full arm movement while the other requires half?

There are many people that would argue that activities like Poker, Chess etc could be considered sports. Some even coin phrases such as intellectual sport to differentiate them from bog standard sport.

Intellectual sport is meant to be a descriptive for a variety of activities, just like e-sport.

For video game, the additional 'e' in front of 'sport' is a clear disclaimer that they are not the same thing. They have similar attribute, hense the borrowed word, but clearly e-sport sits equal in tier with sport and intellectual sport in word usage as a description for a broad range of activities with a common tie in (gaming, physical exertion and mental stimulation respectively).

You're looking too much into the word 'sport' and missing the whole picture.