> Unless you mean digitally, but that's just "having accounts".
But you must open an account with a bank, and deposit money before they can process transactions for you.
There's no way to deposit money *into* bitcoin. Bitcoin is money.
> Each transaction has a set of associated addresses.
Yes, and you suggested addresses are the equivalent of accounts. They are not.
> Banks can facilitate transactions between arbitrary whole numbers of accounts also (off the top of my head: 1- paying interest; 2- payment; 3+- escrow)
Accounts, which hold money, are a tool of banks[0]. Bitcoin doesn't have accounts. Bitcoin is not a (limited) bank. It is a distributed digital cash system.
"Bitcoin uses peer-to-peer technology to operate with no central authority or banks; managing transactions and the issuing of bitcoins is carried out collectively by the network."[1]
0 - https://www.fdic.gov/about/learn/learning/banks.html
1 - https://bitcoin.org/en/