“I am of the last generation who will remember the time before the internet” means “many people in my generation [and no later generation] remember a time when

“I am of the last generation who will remember the time before the internet” means “many people in my generation [and no later generation] remember a time when the internet was not a meaningful presence in our lives” — which is true for those who spent a substantial portion of their childhood before the internet was used by practically everybody. So I don't see what's the objection to it. And what you're calling “weird” and “bizarre” is exactly the author's point about writing to be niche and specific, in contrast to “Writing for a general public, you need to be broad and a bit bland”.