Not a lot of people know this because most people will try to get the problem fixed, but the problem will actually fix itself after enough time and use. The problem with the keyboard design is actually two fold: particulate AND keys slightly out of tolerances. You will notice that the problem almost always gets worse when the computer gets warm. E, C, X, R and a lot of keys on the left side of the keyboard seem to be the most troublesome when it gets warm. The keys expand and start to actually "click" different. The sound is audibly different. It actually drove me crazy when I first got it. It took almost a year for all the keys to have the same tone, and the S key is still ever so slightly softer than the rest.

I have a 2016 MBP and after about 3-6 months I started getting stuck and repeating keys. I was going to take it to the Apple Store to get replaced, but just sort of struggled through it for another 3 months or so as I missed appointment after appointment because I was busy. The problem is now entirely gone and all the keys click the same. I actually had this same thing happen with another 2016 MBP. With enough use, the keys break in and no longer stick.

This is, obviously, a ridiculous solution—if you can even call it that. But an aged keyboard is actually more reliable than a new one.

The fix for this wasn't just adding in a layer to keep the dust out, but getting tighter tolerances on the butterfly mechanism itself and designed around the expansion issue or using different/better materials.

It's somewhat buried in the OP, but if you're having this problem as well (particularly with repeated keys, as I am with a brand new fully-loaded MacBook Pro 2018) and don't have time to wait for your keyboard to "bake," I've had some success with https://github.com/aahung/Unshaky as a customizable software debouncing solution. Having occasional "aardvark -> ardvark" errors from aggressive debouncing of my repeating A key is superior to haaving aall my text look like this. It's not perfect, though, and I've had to delete multiple words in this post even with it on.

I hate how addicted I am to Apple's still-glorious desktop UI, font rendering, and trackpad dynamics. Their other hardware choices make me detest their brand. But there's no other way to get my "fix."