AFAIK, they're not doing "blanket IP blocking", they're intercepting requests based on DNS and IP, and try to serve their own certificates and their own content. Obviously, in most cases it fails, as the certificate doesn't match the site, so the browser rejects it, but as far as I can see and tell, there is no "blanket IP blocks", more like "DNS and IP interception".
The difference doesn't really matter in practice, sucks regardless, but I thought I'd clarify for the ones who are not experiencing these blocks themselves at least.