Not at all - you can still see the paper and know what an apple is supposed to look like. Describing a face or drawing a scene from memory is very hard though.
That doesn't really make sense to me. What does it mean to "know what an apple looks like" without being unable to imagine it? How would that be any different from knowing what a face looks like without being able to imagine it? Do note I said realistic apple [1], not just a cartoonish drawing, so I don't just mean "a squished circle"...
Why would I have to visualize to know whether or not something is an apple? I can recognize one on sight without having to match it up with a visualization in my head, so I can start from the right shape and add details until it becomes an apple. No visualization required at all. Obviously it's quicker and easier to use a model or reference picture, but not required.
I can draw a generic face, but not a specific one unless I have a model or picture. If I had to give a description of someone, even family members or close friends, I would be hopeless other than very basic things like relative height, hair and skin color.
In my experience with aphantasia, I struggle with the ability to describe people based on their physical attributes (my parents for example) but I think it's distinct from face blindness. I can easily recognize people that I know purely based on their faces, but I don't believe that people with face blindness could. I just can't visualize what they look like mentally.
It's a non-issue. I never even realized that it was a thing until I several years ago I was listening to a podcast that involved discussing mental monologues and imagery and thinking "WTF are these people talking about?!", and then doing some research. I had previously always understood things like "mind's eye" and inner voice/conscience as metaphors or some kind of mystical superstition.
[1] Example: https://drawpj.com/wp-content/uploads/2018/05/hyperrealistic...