Communication requires thought and input from both sides - if I use a numeric abbreviation with someone who is unfamiliar with it, I am communicating badly.
I think where we differ is that I see such abbreviations as no worse than any other - TLAs (three letter acronyms) can also be as impenetrable.
To this day I don't know what Eli8 means, and I'm not going to even bother to look it up. It's not communication.