I'll go one step further... Its function to separate a discussion from the original author can often be important.
In the case of hate speech, it's quite common for an antisemite to post something, for a Jew to reply, then get blocked.
Quote tweets allow someone to have a discussion separate from the author. That's the context I see it most in.
If there's another mechanism we can use for similar interactions, please, please show me!
Do we need to use screenshots?