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There are traction/handling reasons people want short chainstays. But there are other benefits of those adjusters.
With adjuster screws set the rear wheel goes back in exactly at exactly the same place, maintaining clearance to the stays/guards/brake-blocks. It's super useful if you run the frame ss/fixed.
It also allows frame builders to eff up there measurements and still have a usable frame!
What benefit do they have on a geared bike? I've got the holes on my geared bike frame but there were no screws when purchased so have always run the bike with the wheel slammed to the back of the dropouts.