Computers, iPhones, etc. are hardly "media"--they're devices for viewing media. As such it's sort of hard to "indoctrinate" kids through them (since you have to actually seek out the content you wish to view). Video games are media, I suppose, but I'm not sure who's supposed to be indoctrinating kids or what precisely is being indoctrinated.
Anyway, complaining that kids don't exercise enough is valid, I suppose, although rather a tired complaint by now.
"We are symbols and inhabit symbols; workmen, work, and tools, words and things, birth and death, all are emblems; but we sympathize with the symbols, and being infatuated with the economical uses of things, we do not know that they are thoughts." - Emerson, "The Poet" (Essays, Second Series)