I don't agree. But, even if I was fully on board with that, I'd say "it's like email" is still orders of magnitude more relatable as an analogy than telling non-technical people it's like a BBS, it's like UDP, it's like, technical mumbo-jumbo that the majority of the audience probably doesn't even know by name recognition, let alone understand what these things are and how they work.

Analogies are rarely perfect (I'd argue good analogies are never perfect).