A lot of good reasons to stick with Bitcoin, esp. Core and keep running full nodes and I also would trust smart contracts a lot more, if they would be based on the the Bitcoin blockchain than on any other shitchain. In my opinion ALL of the > 1000 Alts are rather the result of missed financial/fame opportunities than a real technological progress.
I dont think this would solve the problem that caused these losses. Bitcoin core doesnt have any functionality that keeps track of user balances that are separate and distinct from wallet balances.
To my knowledge, these companies were tricked into signing transactions for amounts larger than they should have. I dont believe there were any issues with the wallet software in that the wallet behaved as it should have the wallet software did not think deposits were received that never confirmed and signed transactions as instructed.
I think the root cause of this is bad business practices. Notwithstanding poor implementation of verifying account balances (and similar) these companies either held way too much money in their hot wallet, did not verify DB balances matched blockchain balances (within a reasonable variance), did not investigate the root cause of overdrafts and/or a combination of the above prior to topping off the hot wallet.