Reviewers prioritize their time above all, and after that correctness,leaving novelty in last place. If a paper comes from a unknown lab it tends to get greater scrutiny because a famous name is a subconscious stand-in for correctness. You spend less time reviewing famous authors because you think they are less likely to have bugs.
Reviewing a paper is effectively unrewarded: you need some kind of reviewing service on your CV, but the amount and quality is barely measured, let alone considered for career progression.
Reviewing a very good paper is quick and easy ("LGTM"). Really terrible papers are not too bad if they're obviously awful, but reviewing something subtly flawed takes a lot of work: you need to identify the flaws and describe them in a way that's compelling enough to convince the authors--or at least the editors. Ideally, you'll also explain how to address them, which is more work now and down the road when you review the authors' often-grudging implementation of your suggestion.
In such a world, people may be increasingly reluctant to review papers without some indication of their quality (for which name is a rough proxy). My solution to this is to somehow make reviewing more valued. It's an important part of science and deserves more than a checkbox.
Reviewing is hard work with very few rewards - and you have to decide at the start whether it is worth your time to embark on it. Ideally we would like to learn something from the paper.
I and most people here would most likely strongly prefer to review a paper written by someone good at what they do.
In reality most papers are pretty bad - thus when we prefer reviewing papers written by Nobel prize winners we are not "biased" and "humbly bowing" before their greatness - we are just trying to make it worth our while.
Reviewers prioritize their time above all, and after that correctness,leaving novelty in last place. If a paper comes from a unknown lab it tends to get greater scrutiny because a famous name is a subconscious stand-in for correctness. You spend less time reviewing famous authors because you think they are less likely to have bugs.