[nebulousthree]

Checks and balances are a perpetual game of cat and mouse. While yes, they do raise the barrier of entry, it doesn't account for nepotism or favouritism, which would be the equivalent of lifting the ribbon to let someone through. It can go so far as to make legitimate attempts at entry unreasonably difficult or downright impossible, making the paper publish only papers pushed through a rigged system that appears on the surface to be of value. It is only through time or by investigation that it is found that a paper reputation is increasingly fraudulent.

[stillbourne]

Yes, and we even have a system for that. Retraction. https://retractionwatch.com/

I'm not saying the system is perfect but it works over time.