It's not that difficult to get a non custodial wallet, write out your seedphrase and store them in a secure place is it? So why would you want to risk the safety of your funds in the hands of centralized platforms?
""NOT YOUR KEYS, NOT YOUR COINS" non custodian wallet are good storage for coins".
It's not enough.
Choosing good wallets to use must have two main criteria: non-custodial (or aka self-custodial) and open-source (aka reproducible) and you only mentioned about non-custodial but forgot about open-source.
It's not hard to get a non-custodial and open-source wallet as it is free to download, verify and install to use without any fee. People either don't know about open-source, non-custodial wallets or just believed in custodial wallets or close-source non-custodial wallets.