Man has been on the moon since the development of virtually every type of shotgun action/lock/barrel development with perhaps the exception of the internal interchangeable choke and the Beretta UGB25 Xcel.
So what ? Dinosaurs are extinct and ice cream has no bones !
"Round the Clock" shooting from a "High" and "Low" House at 21 yards, which subsequently transformed into "Skeet" pretty much as we now know it, was originally devised by a group of New England grouse & woodcock hunters to hone their Upland shooting skills with their SxS doubles.
SxS doubles were at first in vogue as Skeet guns ... closely followed by pumps, mainly Model 12 & 42's - which seemed to dominate through to the mid-50's. By the 60's, the Remington autoloaders, up to and including the Model 1100 was perhaps the Skeet gun of choice. O/U doubles seemed to take hold in the 70's and were certainly dominant in the 80's ... at the top level, with "4-Barrel sets". "Tube sets", including carrier barells for the smaller gauges became the vogue in the 90's and have remained.
For recreation, shoot what you like.
To compete at the upper atmosphere, today it is most likely a Kreighoff, Kolar, Perazzi, or Beretta with interchangeable gauge tubes, mostly Kolar or Briley - and increasingly more so, the 12 gauge event is being shot with the 20 ga. tubes. Barrel length has also been increasing over the years... O/U's were predominantly 26" & occassionally 28's, then almost all 28's, now 30's seem to predominate and even 32's are showing up.
If you're not competing, choose whatever suits ya !