I have bitcoins on cex.io and coinmama.com for two years and I never had problems
and I also have an account in blockchain.com form 5 months
Well good for you and not for the majority. Look the
web wallets board most of the complains are those who have issues for blockchain.com wallet, while they are still somewhat good for small amount use.
And for cex.io, well they still somewhat resolve those problems from their users but arguing that it's an exchange that needed for KYC verification for storing your funds and cannot even fully control your own funds and such way for alternatives for multiwallets? no way.
Christ people really just won't listen to the news or learn from other people's mistakes, will they? Mt Gox alone should have been enough warning, biting the ass of veteran members and guys who are personalities today.
Sure I keep some stuff on exchanges or online services too but for the former they're worth next to nothing, amd for the latter, because I need to keep funds there to use their services (though I have to really evaluate every month whether I need them).
All it takes is 1 problem and it doesn't matter how long you've had funds on some platform "without any problems".