Tabs are why I never switched away from firefox. Tab groups are brilliant. I actually do usually have around 9 or less tabs in a single group.
But article is bullshit and completely missing workflow of people who like to open many tabs. Hell, I usually have 4 or 5 app tabs just for social networking/email. It's not about looking at stuff simultaneously, but about organization, breaking down tasks into smaller pieces, and not fricking having to remember what the heck I was reading 30 minutes ago that might be a solution to my problem.