It 's a combination of three factors:
1.- In the reel: light spool, shallow spool design and freely rotation spool support bearings.
2.- The line: less diameter line ( which doesn 't necessarily mean you gotta fish with hairthin like line )
3.- The rod: limber rods ( less power ) that can load up with lighter baits.
The Chronarch Mg has a lighter spool ( with lots of holes ) with shallow spool ( don 't hold much line ) and more freely rotating spool supporting bearings ( ARBs, not because they are corrosion resitant, it 's because of the bearing design ).
Nobody is saying you can 't cast light lures with other reels, you can, but not with the ease and the performance the Chronarch Mg can, if it serves you as an example, I can cast a 1/16 th oz bait with a Curado 200B with 10 lbs test on a GLoomis CR721 but for starters I won 't even be close to the distance I can achieve with the Chronarch Mg, needles to say that you gotta be really good at fine tunnning the braking and tension plus a very well trained thumb.