The peculiar way the message in a bottle modus is able to store ectoplasm would seem to further emphasise ectoplasm as a substance that exists purely on the material layer, with little “ideological” substance. The sylladex is a system that operates primarily in the realm of ideas, “and devices that trade in these platonic concepts can understand nothing else.“ (Homestuck: Book 3: Act 4 commentary, p.37). In other words, ectoplasm isn’t something you can record on a piece of paper; it’s pure substance that can only be held in a receptacle, like a bottle.

To look at this from another angle, captchaloguing an item, in plain terms, logs that item as a captcha. Since these captchas are limited to 8 characters in length, there’s a limit to how many items can possibly have codes and therefore, presumably, how many items can possibly be captchalogued. If someone’s paradox ghost contains the whole of their DNA, and the number of possible biological organisms outnumbers all the possible captchalogue codes, then it stands to reason that an item this complex simply could not be captchalogued. It would have to be “compressed” in some way to fit the 8-character code length; or in more Platonic terms, the paradox ghost would have to be made more “basic”, more similar to the fundamental idea of a paradox ghost.