And no, I don't agree. I think leadership has to be open to challenge, and political parties may have boundaries but that enforcing groupthink is bad.
So the SNP shouldn't prioritise candidates who support Scottish independence over those who don't support Scottish independence then?
Or is that on the wrong side of your
boundaries? If so then why isn't the Labour leadership also permitted their own boundaries.
If you understood anything about the Labour party (I suspect you don't but I was a member and activist for many years) where there is a sitting MP who wants to stand again the decision rests pretty well entirely with local membership and local affiliates - if they don't 'trigger' the MP then they are selected again as a candidate. At most elections, this will be the situation for most MPs.
So this is only in situations where:
1. There is a sitting MP but he or she doesn't want to stand again.
2. Where there is no sitting MP
3. Where there are boundary changes which mean it isn't clear whether there is a sitting MP or where two sitting MPs fight it out.
So the party cannot make wholesale changes to the composition of their MPs as even if there is a big swing a large proportion we be re-elected MPs where candidature rests with the local party and local affiliates entirely.