Never mind my opinion. Luno may seem like Coinbase.com, but Luno is not even a custodial wallet, it is an exchange. I lately checked it on coinmarketcap and see it to be the 157th exchange according to exchanges trading volume.
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Coinbase encourages people that do not know how risky to backup on online/clouds exactly just like you commented. I hate coinbase because of this. Also, I hate coinbase because it is difficult for many newbies to know the difference between coinbase.com, coinbase pro and coinbase wallet app. But, upon opening coinbase wallet app, it will give you choice to either backup online or manually, manual backup will only let you to save the backup offline just like the way you do recommended.
Other reasons I hate coinbase wallet appIt has a username, and not only that, they are also encouraging it to be visible to other users.
Coinbase will not have to make governments suffer from compromsing users privacy, what is the difference between governments telling exchanges users to register their noncustodial wallet with the exchange they are using and this one, they are just the same thing. Many people will press connect to coinbase which is just a simple way to automatically register the coinbase noncustodial wallet. No privacy.