Because it barely spends any time setting that up, for one thing. It would probably be a bit more memorable if the characters actually said things like “Hi! I’m Compugter! I sit on your desk or in your lap and talk to the Internet for you!”; instead there is just a panel with a tiny label floating off to one side.

Or maybe it should be “Hi! I’m Compugter, I sit in a rack in a puppy farm somewhere, and talk to the browserbird in your hand or lap or desk”? It really doesn’t define its terms at all before launching into a description of a man-in-the-middle attack. This is just not well-written, and no amount of cute drawings will cover for that, no matter how well done they are.

I have this problem with most analogies used to explain things. Computer concepts are abstract enough without layering another abstraction on top. If you're trying to explain something complicated, you're just adding more cognitive overload. If you're trying to explain something simple, why not be direct? It's possible that I just run into nothing but bad analogies, but I don't see them as being helpful.

I had this issue even starting from the first panel after the introduction, where the dog was sending a message to the bird. I kept having to scroll to the top to double check who was who.