API RPC request to get Account Balance

Why the balances.account RPC request on storage, always return an empty balance ?
As a workaround, I use system.account on storage, with the expected result.

Account used for testing : 5FH48744BHgNoLBe8syGXbTEnSpGhp8ttdAKW4MWcR7TUKai

balances.account: PalletBalancesAccountData

{
  free: 0
  reserved: 0
  miscFrozen: 0
  feeFrozen: 0
}
system.account: FrameSystemAccountInfo

{
  nonce: 1
  consumers: 0
  providers: 1
  sufficients: 0
  data: {
    randomId: 0x18a4d1f77688a63a6213a8e7f7469c836c0a90a6327f6f24b517ed46b3c60f57
    free: 9,799
    reserved: 0
    feeFrozen: 0
  }
}

Élois told me that they [Substrate people] want to decouple balance from system but it’s not yet finished. So the balance pallet still contains unused stuff, duplicate of currently used stuff in system.

You also see the custom data from duniter-account pallet, for example randomId. I have a branch to remove it since it adds a lot of complexity that I find more harmful than useful right now (MaxNewAccountsPerBlock, PendingRandomIdAssignments, PendingNewAccounts, RandomIdAssigned…).