Such exchanges have a limited shelf life.There aren't any people in charge. People don't act quickly enough to shave off those vital nano-percentages in split-second trades. It's all algorithms.
Some finance companies have built microwave relay networks to link them tomthe exchanges because broadband, which travels at the speed of light, is too slow for them.
Time and time again, centralised exchanges cause loads of problems to the detriment of customers a long time before the regulators manage to sort the problem out.
Algorithms aren't the real problem. Large entities being sold a back door to front-run the little people are the biggest problem.
With decentralised exchanges on the blockchain, there are no secret back doors. Everything is all done out in the open.