I'm genuinely asking to learn. - But couldn't developers already store arbitrary data within the blocks if they wanted to before Segwit? I remember there was a marriage certificate "in the blockchain" and other arbitrary data.
Yes, through OP_RETURN, fake address and other means. If you also interested with the historical usage, check
https://www.righto.com/2014/02/ascii-bernanke-wikileaks-photographs.html.
Plus have there been proposals from the Core Developers?
Have you forget these PR?
https://github.com/bitcoin/bitcoin/pull/29769https://github.com/bitcoin/bitcoin/pull/28408A person who uses Bitcoin in a way that you don't approve of, but paid the fees for block space, and followed the consensus rules is not a real Bitcoin user?
Whether they're real Bitcoin user or not, it's clear their transaction isn't created with goal of sending Bitcoin to someone else.