MEMS have been used in cellphones for years but haven’t been capable of integration into earbuds until recently

This is all you need to read in the article to see the author doesn’t know what they’re talking about.

MEMS microphones have been used in cellphones and earbuds for years, because they are a mature technology that works very well and provides miniaturisation potential.

MEMS drivers (loudspeakers) are not used in smartphones at all because there is a very limited environment where they work well.

In short the reason why this is the case is because it is an awful lot easier to make something very small which can be moved by moving air rather than something small which can generate movement of air.

MEMS are miniaturised machines which use the production technologies of silicon chips to make mechanical systems at a micrometer scale. Instead of using a saw or press to cut pieces out of metal, you use photolithography to make them out of silicon, and make them extremely small.

Driver = loudspeaker

A MEMS driver is a loudspeaker which is made at a micrometer scale. They can work really well in very specific environments, but earbuds are not always (maybe never) used in exactly this perfect environment and so it’s risky to use MEMS drivers because placing the earbuds slightly wrong in your ear will make them sound awful.

Creative is taking a risk with this product, which bigger manufacturers will not take until at least several generations of MEMS driver have passed.

I have worked in the audio field with MEMS in the past. Unfortunately MEMS drivers are not all they’re cracked up to be, they dont have the same miniaturisation capabilities as microphones.

The main issue with voice coil drivers in headsets is size and power consumption, particularly for low frequency reproduction. Drivers need to shift a certain amount of air to generate signal power = audio volume. Shifting the air requires both power and surface area. There is actually very little room to improve this in free-field.

Where there is room to improve is when you have a sealed cavity. Air behaves differently in a sealed cavity, so a small driver could potentially generate a lot of signal power. Unfortunately very few earbuds actually create a perfect seal in everyone’s ears, and many people don’t wear them properly. Therefore the biggest earbud makers will not consider a MEMS driver until it can produce acceptable signal quality in a cavity which is not properly sealed, because there is a lot of risk for people to have a bad experience and spread negative publicity due to using the earbuds wrong.

TLDR: MEMS drivers are only advantageous in a sealed pressure cavity, which is not always the case when wearing earbuds, and so they are unlikely to become mainstream until they have been further developed.