I can get if this case is for like travel and going out where you're not gunna be on your phone constantly.
But I've had a case like this (a little smaller but still pretty bulky like this) it's just not practical in my opinion for everyday use or if you're on your phone a lot.
I also don't like the idea of keeping everything you own, literally, where you keep your phone.
If you lose your wallet, you just lose your wallet. You can cancel or shut off your cards.
But if you lose your phone AND your wallet and loose money, then you've done and lost everything.
To me it Doesn't make sense to keep them together like that. When you need your phone, you literally don't need your wallet. So if you're constantly taking your phone out and your wallet is connected with it, it's just more chances to lose your cards when they should be in your purse and only taken out during purchases.
That's easier to keep track of if you lose it too. But if you have a case like this, constantly pulling out your phone, then who the fuck knows where you lost your debit and credit cards. Shit could be anywhere.