easy as in you can go to https://opreturnbot.com/ and put in whatever you want. this uses libre relay as their backend.

if you want something custom you can just download librerelay and send it that way.

people creating large op_returns with image data need to be somewhat technical anyways. if they can do that then they can download librerelay and broadcast it to a miner

there is no "upload jpg" on the bitcoin client, you will be using custom software regardless. and it can be as easy as a website. knots doesn't do shit all to stop it.