[Yo-Yo]

So what is the advantage of a MEMS clock vs. a quartz crystal?

[Swordmaker]

So what is the advantage of a MEMS clock vs. a quartz crystal?

Uh, Helium detection?

[Menehune56]

So what is the advantage of a MEMS clock vs. a quartz crystal?

The link on iFixIt from the original article on Motherboard is well worth reading. This is their explanation:

But quartz oscillators have some problems. They don’t keep time as well at high (and low) temperatures, and they’re a relatively large component—1×3 mm or so. In their quest for smaller and smaller hardware, Apple has recently started using MEMS timing oscillators from a specialized company called SiTime to replace quartz components.