How poorly do Vitamix blenders grate/shred/slice winter squashes? pertains to just Vitamix blenders, and so is more specific than Blender vs food processor vs juicer.
The answer to the duplicate question is (basically):
The three types of appliances you have listed have different primary uses, and best purposes, although they have some overlap in their capabilities.
This also applies to any specific blender (such as a Vitamix).
A question that is more specific than its duplicate isn't necessarily better. For example, we also close questions like "I left my raw chicken in my car overnight, can I cook and eat it" with a canonical food safety example. I do not see this as any different.