Visiting StackOverflow with partial external request blocking results in a red error banner across the top of the page with text like this:
I expect to see:
The original message brings back the frustration of "An error occurred. [OK] [Cancel]" If I know which domain is the culprit, I might be able to fix it; knowing that some domain on the Internet is the problem? No hope there, no domain to whitelist, nada.
With the domain, I can consider whether I want to unblock it, and do so. If it's warning about a domain I don't care about, I can probably rig up a way to hide the error message on my end, or just suck it up and know that it's Chicken Littling. As it stands, it's either allow all requests or none, and I'm not - and some users on some networks might not have the option of - doing the former.