If I put a user on my ignore list, I don’t want to see or know about their posts. Their posts should be totally invisible, not replaced with a garish highlighted yellow box.
If you block someone on Twitter, then if they send you another message, Twitter doesn’t tell you with a big loud notification saying “HEY, THAT IDIOT YOU BLOCKED HAS SENT YOU A MESSAGE, CLICK TO REVEAL IT!”.
Yet that’s effectively what this site does. Sorry if I have missed a setting somewhere which turns this off.