these never seemed to catch on in the offroad world... i used to run a few lizard skins products on my mountain bike that worked very similar. i know they've had these for the car world for quite some time as well.
https://www.lizardskins.com/product-..._protector&v=0
i believe the main consensus against them was that they tend to trap dirt, debris, and moisture within the assembly, which doesn't exactly exacerbate wear(compared to a non-protected shock), but doesn't cut down wear enough to justify the product.
my impression is that it's led to being a 'feel good' product that has no significant mechanical benefit...