No the author seems opposed to the idea specification of ACME, not just the implementation of the clients.

And a lot of the complaints ultimately boil down to not liking JWS. And I'm not really sure what she would have preferred there. ASN.1, which is even more complicated? Some bespoke format where implementations can't make use of existing libraries?

This is exactly the impression I got here.

I would have had sympathy for the disdain for certbot, but certbot wasn't called out and that isn't what the blog post is about at all.