Right now, not too many providers support these auth protocols, even though they are more secure than current 2fa alternatives and provide a better user experience. The aren't widely supported because that costs development time and many of their customers don't have security keys.
Customers won't buy security keys because it's an added cost that isn't supported by many websites.
The author of the post briefly mentions SoftU2F at the bottom of the post, but it's important to recognize how significant SoftU2F is to the U2F ecosystem.
We're just now starting to see consumer hardware come with HSM's built in. Apple SEP, Intel SGX, etc. are examples of this. SoftU2F _will_ be able to leverage these consumer HSM's to do secure crypto operations - see the pull request at [0] about storing keys in the SEP. This will effectively put U2F and UAF capability into the hands of your average consumer with no additional cost. Things can be just _built-in_, which is what it'll take to start seeing increased protocol adoption across browsers and service providers.
I'm stoked about the future of security keys and the associated protocols. Both external keys and HSM's built directly into consumer hardware.