It's not discrimination. It was disabled many years ago for newbies because people were registering new accounts and abusing the feature to embed gay porn or something like that, which was against the rules, if I understand correctly.
Some posts from theymos, I quoted one but you can find some more in that thread.
From 2011, 2015 to 2017: Feel images annoying, ban them, and give a solution with Copper membership for lifting the restriction on non spam newbies.
I don't like embedded images. They usually clutter up the discussion without much benefit. This is especially true of signature images: they take up more screen space than a few paragraphs, but they provide almost no value.
Due to abuse, newbie-posted embedded images are now disabled on these pages:
By popular demand, newbies can now pay to have some of their restrictions lifted. If you pay the fee, you become a Copper Member, and you can post images. That's the main point of this: allowing newbies to post images.