The only problem that I see with this is that images and especially videos take up vastly more space than plain text.
And does ActivityPub include client APIs? I haven’t looked at it, but my completely unfounded impression has been that it only handled server to server communication.
My cousin programmed a simple labyrinth game on my C64 by randomly placing symbols on the screen and you had to get the cursor from the upper left corner to the lower right without bumping into a symbol.
I was so impressed.