Take nothing away from Dirt Merchant, he was doing SKB action jobs before they were popular.
That said, I can see where a stuck hull might be a little bit easier to shuck with a unified extractor versus a split. No over governing evidence, just my thoughts, be that right or wrong.
When two split extractors are welded together there is one moving piece, versus two moving pieces doing the work. I would imagine that the welded one piece is more reliable and efficient then two. Speed aside, I am referring to consistency in doing a particular job.
Any game is about efficiency, the fewer unknowns or moving parts one has to worry about.... the more focused one can be. Another example is the Ruger Vaquero transfer bar....Some shooters say it works perfectly and are happy with leaving it in, other shooters remove it, do to the potential risk of breaking during a match. Shooters choice.
Any way you look or feel about it, shooters get to do, (within the current laws) what they think will work best for them.
Great sport.