U-joint vs pot coupler

Sliding into curbs during winter weather.
Being driven to woods parties by high-schoolers.
Untold amounts of dirt road/washboard gravel driving.
Smacking into parking barriers.
Hitting speed bumps too fast.
"Wendy, I can fly!"

These are all things these cars endured when they were someone's primary driver, and the steering coupler shows some wear (slop) by the time we get 'em, often with a rolled odometer. Rebuild it, and it feels as solid as a U-joint. Subject a U-joint to that same treatment, and I'd bet it would rickety junk by 30K miles. Great in a tube chassis, not ideal for a unibody.

But most of us don't treat these cars like that anymore, so it's less of an issue. @72bluNblu definitely has a very well-considered U-joint based solution, though.