This does have something to do with Refresh Rate. Being that regardless of the rate Set, for benchmarking purposes the game will only ever render 60 new frames per second.
I think you need to emphasise that NEW bit some more. Without vsync for example, you could quite easily render 100 frames in a second, but there will only be 60 unique frames in that set, because the game data has only updated 60 times in that second.
Personally, I'm a little disapointed. I would've preferred it if the game tick was adjustable, to say 30hz, 60hz, 85hz, and 100hz. Otherwise you're gonna get a jerking problem on smooth moving objects.
For example, if the game tick is 60hz, and you're rendering at 100fps, on a 100hz monitor, with vsync on, then you're gonna get an old frame, every couple of frames, giving a jerky appearance. Theres no way on earth it will sync correctly. 60hz updates viewed through a 100hz window, is never gonna sync properly.
So if you want the absolute smoothest option you will have to set your monitor to 60hz.
It probably wont be noticable to most ppl, but it will still be there.
Caps are always bad for these types of reasons, but I understand it makes physics, and jump prediction alot easier to code. This is one of the reasons pro q3 players use insane frame-rates, because it makes them reach certain jumps you just cant do on sub-100fps situations.