1 motor vs 2 motor axis

I'm curious if there's benefits and cons I'm not aware of on a 1 motor with a long axle driving two sides of a single axis vs 2 motor setups.
It seems like a single larger motor driving both sides would ensure perfect alignment at all times yet most tables I see use two independent motors for the Y axis.

What's the story?  Does a long axle or axles give too much mass and cause error?  Is two motors just easier?

 

-Work involved comes to pretty much the same, depending on tools at hand
-1 motor in general cheaper than two smaller ones as it does require also 2 drives for gantry squaring
-Moving mass again pretty close to same
-wiring more work for 2 motors
-configuration takes the same time, maybe tuning the squaring takes a bit more on the 2 motor setup
-on longer distances, the rotating shaft will vibrate at very low speeds, hence limiting velocities, or adding more support bearings along the way, and that in turn takes time to have the bearings lined up properly and adds more load to motor
-1 big motor cases more vibrations than 2 smaller ones, if using steppers
-2 motors and wiring makes the machine a bit more susceptible to interference, especially for Plasma
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Cant think of anything else for now...

Plenty of commercial tables have used 1 motor in the past but motors today are relatively cheap and alignment in software is now trivial. 2 motors I think is easier becasue you need to mount the shaft so it can go across the table. Probably along the gantry. You then need to get the drive to the pinions unless you use belts the full length of the table.