Unfortunately, most of the mechs do this. Designs such as Sub Ohm Innovations, Broadside, 2JNT, Purge Slam piece, et al do in fact have contacts that do NOT make and break on battery terminals at all. Using an 18650 adapter in a 20700 or 21700 mod also prevents making and breaking on cells directly. Constant pressure on battery terminals results in less battery wear/damage and un necessary battery heating from associated power loss at the terminal point. I've been using my 2JNT Pilak Tycoon for nearly 3 weeks nonstop and pulled out the switch to check the contact area and it's perfectly clean as the day I got it! And (of course) the batteries look perfect since they make constant contact on both positive and negative terminals the entire time.
And threads should never, ever have arcing. Just as there should never be any intermittent connections (interruptions) along a circuit that's NOT intended to disrupt the flow of electrons. If there's intermittent connectivity in your threads you have a serious design flaw! Some mods may indeed have arcing in other places besides where make and break occurs at the battery terminal. I've seen cloned AV tubes, due to the sloppy tolerances around the firing pin, for example, get arc marks between the firing pin and ring where it travels. That's one area that was addressed in the Dreamer mod.
With high current designs, the best way to keep arcing to a minimum is the open and close the contacts as quickly as possible. This just isn't feasible with the simplicity of a mechanical mod. And most people wouldn't like the snap noise that would sound similar to say the piezoelectric igniter found on a gas grill which employs an impact principle to increase spark energy.
Here we can see not only the significance of AC vs. DC (which doesn't apply to battery powered mods) AND arcing on make and break.