In my ideal world, "mute user" is a protocol reaction, and I have a bot that I configured to mute any user who replies with specific keywords. The bot has a website where I can go and mute/unmute users too.

Dad, geek, conversation liquidity provider. vrypan.net (home), /weatherxm (work), @l--o--l (fun). Also https://paragraph.xyz/@purplesubmarine

Yes & 
Why aren’t all Actions Reactions?

🎩🍌Ethereum builder & people connector. @juicebox revnet.eth.limo defifa.net d33m:liv

Yes exactly. Every Action dev should have the option to store ‘reactions’ onHub. 

I’m not Liking your wc Gm, I’m Gm’n back.

There is a plan for "extended reactions" that will allow an app to write more expressive reactions to the protocol. (If this is what you mean).