in the end you are talking about a web wallet and this type of wallet is always going to be the weakest and least secure wallets among the rest of them.
I agree!
Claiming to be the most powerful bitcoin wallet doesn't guarantee just because they have the biggest hashrate or what makes them powerful.
Web wallets are still categorized as one of the wallets that has less security.
I haven't tried using btc.com's wallet but I have tried other web wallets such as blockchain.info.
I wonder on how many users they have.