gets an A on their browser and phone apps, which are perfectly linear in reverse-chronological order. But their tablet app presents users with two equal columns of content. I give their tablet app a D. Why they chose to go two columns on the tablet is a mystery.

You'll note that these examples of bad, multi-stream design are all sites or apps that you could argue are very successful, thus invalidating my premise. But the same could be said for Facebook, and that company is apparently fixing its multi-stream problem in order to keep expanding into the larger mainstream user base.

Multi-stream social content feeds tend to be appealing to technical people, early adopters and tech pundits, who drive the early success of some of these apps and create a false sense of confidence for the companies who make them.

But the larger market -- stressed out, type-A personality "skimming" executives, older people less comfortable with screen clutter, non-technical users, teenagers, people reading content in a second language -- who collectively make up the "mainstream" user base will choose a linear interface over a non-linear one.

When the dust settles on the ongoing war over eyeballs in the social content space, the winners will all have linear, single-stream content interfaces.