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Know what ports I haven’t used even a single time? Thunderbolt/Displayport.
Which Thunderbolt ?
All current iMacs have Thunderbolt 3. Pragmatically, Thunderbolt 3 ports have a USB mode to them also. So there are six ports with USB mode possible. ( iMac Pro has eight. )
However, if there is a require for more bandwidth coupled to additional ports then Thunderbolt is a solution. USB Hubs drag data speeds down to the lowest common denominator on active devices.
For example:
7 more USB ports (pragmatically over 3 USB controllers ) .
https://www.caldigit.com/ts3-plus
along with easier to reach headphone and SD card slot than standard iMac ones. [ Which will show up in your survey as folks leaving USB cables plugged into the back of the iMac all the time to make it easier to intermittent things like charge phone (or some other Apple Lightning device ). Similar issue off onto powered hubs (more power than hub actually needed. ) ]
USB 4 makes Thunderbolt an even higher likely weaved in option. ( standard leaves some outs for system vendors looking to minimize costs similar to how Type-C required minimal is USB 2.0 ). More Thunderbolt is coming to all classic form factors PC systems going forward.
Thunderbolt 2 solutions are more problematical at this point; at least for new options appearing on market. Apple waiting all the way into 2017 to move to TBv3 on the iMac makes that problem incrementally bigger.
What collection will probably show is that most folks don't have high bandwidth requirements ( 5Gb/s is "fast enough" for lots of folks. ) and that most folks can get by with just one screen. Thunderbolt is an option if they more out of that state or sell/transfer machine to someone who is in a higher bandwidth needs state. For example, if later need 10+ Gb/s USB device can get there with Thunderbolt. You won't on an extreme hub hooked to a legacy generation USB controller.
Laptops are great, but Desktops are where the money is.
Maybe in a narrow corner of the Windows ( or Linux ) PC world.... 70+ % of all Macs sold are laptops and all of them at substantive profit.