FWIW:
Still don't know how to content-ignore (e.g. vs spoilerific material, or something flame-bait-ish but also catnip-for-me, that keeps burning me).
But user-ignore's are a thing:
In your own "user profile" the sidebar of options on the left (on a fullscreen, dunno for phone users) there's a "buddy/ignore" list.
By default, you see the "buddy" list. Click to change to Ignore list.
Add usernames you want to ignore.
You will still see that they posted -- they aren't "invisible" to you -- but not what they posted, though each message has an option to show that message. Conceptually, it's rather akin to a spoiler-block: you have to take positive action to be "spoilered."