Do you know if council members can be re-elected? Does "new council" imply a brand new set of council members? If so wouldn't that hurt institutional knowledge?
Because in any discussion about "new councils" ever, it never means that the entire council would be different. Be it a parliament, city council, a church committee, or a software project — the point isn't who is in it or for how long but rather that an election (or any other sort of opportunity for rearrangement) has been held.
"New council", in this circumstance, is shorthand for "holding an election for the council".
Well, it creates a way for other members of the core team to replace someone they disagree with without having to call for a no-confidence vote all the time. I don't know what you mean by "revolutionary", but the point of these kinds of councils is to uphold the vision and principles of the language, and so long as the people in the council are making the correct calls in those regards, there would be no reason to replace them.
"New council", in this circumstance, is shorthand for "holding an election for the council".