As I understand it (I never want notifications so don't have any experience with it), it's only blocking new sites from asking to send notifications. So if you find a site you want notifications from, you can change that back to "Ask" temporarily, allow for that site, and then change back to "Block" for all sites by default.

Note that that behavior might be different on mobile vs. desktop browsers, but again, I don't really know how to test, sorry.