As part of McGonigal’s counter argument, which groups does she identify as the opponents of her

A group of non-gamers

Explanation:

Jane McGonigal wrote a book called “Reality Is Broken: Why Games Make Us Better and How They Can Change the World” in which she brings counterarguments as she explains that gaming is an intricate part of human existence and that it helps to fulfil some human needs, not just in present times but also in ancient times.

She observes that her opponents would be the nongamers who believe that gaming is a waste of time.