I don't even think pp is that straightforward. Not every pp child is a low achiever, with the odd exception of a high achieving pp kid. The problem is that many pp kids don't get the same quality of school, and are often the victims of low expectations. And iirc one study found that a higher achieving pp child only benefited from the pp funding in something like a third of schools.
It seems to quite often be ignored that the pp gap is an average on population level, compared to the none pp population. Pp kids are often behind none pp children of the same ability, but that applies across the whole ability spectrum. Rather than all pp kids on an individual level being behind population average.
I also strongly believe that closing the gap should mean raising the achievements of pp kids, not simply narrowing it by holding high achievers back. I also find the assumption that high achievers and pp kids are often viewed as two entirely separate groups rather offensive. They aren't, bright pp kids aren't exactly hens teeth.
Especially in areas where schools vary greatly in quality, equality of outcome could (and does) mean further disadvantaging brighter pp kids to benefit the lower achieving pp kids, which is wrong.
bubbles There are lots of bright dc who aren't held back in schools and for whom the normal extension work is suitable. However this has no bearing on the fact that in general the top 1/2% aren't having their needs met.
Fair enough that the top 1% won't ever fully work to full potential at school, but it's also not fair to ignore their needs so completely that they are put off education entirely and never maximise their potential after school.
I also firmly believe that unless you've experienced it yourself, or witnessed it in your dc, few people really understand how damaging it is to constantly find school work far too easy.