I mean, they use a quick link, but since the only time you should be opening a quick link is in the shop, and you need a chain tool to shorten the chain...
(It's a moot point, anyway. They're no longer producing pins for 12 speed chains, and they are phasing them out for 8 and 11 speed. They will disappear eventually.)
The problem with dropping their chain on 12 speed is that the quick link only works with their own chainrings/chainrings designed for HG+ chains. I find it amusing that after years of SRAM passive aggressively changing little things to be incompatible, Shimano did the same thing. (case in point: I hope that the SRAM 'engineer' who designed the flat top chain gets every chain tool that they suddenly made obsolete shoved up their bum. They'd probably like it.)
Honestly, the only thing keeping Shimano from burying SRAM is 1) marketing, and 2) getting slapped with anti-trust stuff.