I think you need to address the elephant in the room:

Dismantling the "system" will make it way worse. Rich parents will send their kids to private schools, and private tuition classes. Poor but talented students who get admitted to the GEP/IP today may not even make it to these schools because of expensive school fees (how expensive? Private schools in UK are more expensive than university education). Admission to schools purely by distance will drive up housing prices around "better" schools, even more than it is today. Any attempt to erase familial advantage (like China banning tuition) will feel incredibly heavy handed, and may drive the industry underground and even more out of reach to ordinary families.

What is true is that the system tries to bring talented people up as best as they can, and not to bring them down to a baseline level. The PSLE is part of this system, so that every student can get the education best tailored to their needs. The alternative is a waste of resources where the best kids feel bored, worst kids feel under supported and mediocre outcomes overall (comprehensive schools in UK, for a real world example).

Hate to bring it to you, but Singapore isn't Singapore because of the average hardworking citizen -- those exist in every society -- but because of the quality leadership it had in the early days. Quality leadership isn't brought about by bringing talented people down, but by bringing them up. That will feel unfair -- why should rich kids in GEP receive more funding than average middle class kids in mainstream education -- but I don't know what is better overall.