Yes, I agree here. On centralized exchanges, you should not keep all your funds and generally use the exchange as a wallet. This would be an extremely stupid decision. But still, in the case of trading, the phrase Not your keys, Not your coins! is not entirely applicable, since some part of the funds will have to be kept on the exchange. Those who claim that you can constantly withdraw and deposit funds in order to expose yourself to less risk, most likely never traded on the exchange, because this is still nonsense. But the frequency of conclusions still needs to be increased.
Surely, when it comes to cryptocurrency trading, everything is different, everything is perceived differently, including the attitude towards matters of self-custody of your own keys, undergoing KYC procedures, privacy, anonymity, and security. It's all about compromises and sacrifices: you have to make them if you are to choose between the casual usage of cryptocurrency in your daily life and the professional usage of cryptocurrency in trading, investing, business... You can't stay anonymous while living off trading, you can't avoid KYC and other similar procedures, you can't retain privacy when filling out your tax form, you have to hand over your coins to access liquidity. However, those who are not traders can and probably should avoid taking risks of dealing with centralized entities.