> the fact that the critic has a different input and doesn’t have their own text that needs to be defended.

Different inputs are one point, but there is another problem: lack of diversity

Models from the same maker, share the same training and the same implicit bias. It is like if both reviewers had the same gender, race, and studied at the same university, and just got different book day before. Add fresh immigrant from rural asia, you get VERY different opinions, even with the same input book...

Plus practical aspects, Opus 5 is sometimes way too creative which is good for writting. GPT Sol is complete oposite, it is obsessed with crossing every T and verifying every dot. It complements Opus as reviewer!

If opus gets security sensitive questions, gets downgraded to sonnet and againdown to haiku, the same model will hit the same security block, and will not catch the issue. Model from another lab will very likely catch this.

Plus anthropic models love to smell their own farts, load bearing seems are fantastic...