Agree.
On a certain level, many of the issues discussed by posters above seem connected - or at least appear to contain echoes of - an issue @TheOtherPhoneIsHere flagged very early on, namely: opacity.
In her/his comment, I understood the critique/concern to be focused on exam performance on early stages of the multi-stage indie admissions process.
That said, it seems, to me, at least, tied to a broader trend:
Perhaps it's something limited to a certain cohort of indie prep schools, but there's a strong emphasis in the London preps I'm familiar with on not providing anything to children - or parents - that might allow/incline them to compare performance within the classroom/year cohort.
Children are told not to share or discuss 'assessment' results of any kind - not to talk, at all, about their performance on anything involving marking. To see those things as personal indications of growth rather than inputs used for ranking.
In some, that idea is so entrenched that, on the open morning before the 11+ exams began, children's maths notebooks weren't available for parental review alongside their other work - the fear being, apparently, that parents would compare their children's work.
Even the results of broader testing - the CATs for example - are often treated like state secrets.
I'm torn on this.
On one hand: I celebrate the idea of day-to-day learning not being linked to 'performance' - of children bring able to make mistakes (and learn from them) as a function of their understanding of subject matter without the sense that they're being ranked as a result.
On the other - which plays into the issue of parents applying to a huge number of schools - with that degree of opacity, one can understand that it might be very difficult for parents know which schools to apply for given a total lack of understanding re: their children's standing amongst a given peer group.
All of that would seem to be amplified by the fact that many secondaries give no official, explicit guidance in terms of the sorts of (first round) scores they consider admissions baselines - meaning CEM or ISEB - nor any historical average (or range) of the CATs of admitted children.
Given how many parents are buying into the assessments proffered by Atom and others, might selective secondaries releasing that kind of data not be helpful?
Asking - not suggesting. Because really do wonder.