It’s not a terrible metaphor when it’s the closest thing we have to explaining this issue to a layperson.
You believe the audience for a blog about being tired of multi-tasking is young people, from this new generation that is always multi-tasking (on the smartphone, talking to multiple people, etc)?
You honestly believe they need a metaphor like "single thread versus multi-thread" to grasp the idea of what doing multiple things at the same time means, practically?
If you do, ok then. Who am I to disagree?
I still think none of this makes sense, and the metaphor sucks.
C'mon.