I am beginning to understand the mechanism of bitcoin blockchain, and I was wondering something.
The transactions history represents the 'state' of the bitcoin at any point (or EVM according to the Ethereum whitepaper).
Blockchains address the problem of double spending by recording ALL transactions ever done using the particular currency in the blockchain, from genesis till date. Inevitably the size of the chain keeps increasing and will continue to do so indefinitely.
My question is, why is there a need to track transactions? Why cant we just track the balance in every account?
I understand the problem of double spending, and how a person can try to spend the same money twice. We associate the balance of an account with a public key of the account. the transaction history provides us with a way to track the balances.
But why cant we discard the transaction, and just store the remaining balance after verifying the transaction? Why does the 'how the money got there' important?
Why is double spending an issue with this approach (because if a transaction is verified, then the balance in the account must go down?) What I am asking is, why cant we track ALL ACCOUNTS instead of ALL TRANSACTIONS? (this way the blockchain size is a function of number of nodes, not number of transactions)