@HAK I think with everything it is nuanced. In my personal opinion (you do as you feel is right) blocking is only acceptable if you politely ask someone to disengage and they dont. A proper respectful society at least attempts to discuss things civilly before resorting to more heavy handed tactics.
As with anything too much can be abusive towards others, too little abusive towards you, there is a balance to be had.
As I said, a civiized society would disengage when asked. So if an account you deem as misinformation tries to debate you then you should say "Please dont contact me about this, i do not wish to ever discuss this with you", and which point that should be honored and you'd never hear from them again.
I am not suggesting you have to invest even a moment of time on anyone that wouldn't be of value to you beyond the simple courtesy of expressing your desire to not engage.
In a civilized society blocking shouldnt ever be needed because people respect your boundaries. If those people are acting uncivilized and not respecting those boundaries then blocking is the logical next step in my mind.