Need clarification regarding to transactions

Question

Sorry if question is duplicate . I tried to find answers in google but I don't know \how to search really . Here is my problem . Basic Smart contract gives you some sort of API to communicate with blockchain , when using in it's method

 var MyContract = web3.eth.contract(abiArray);
var contractInstance = MyContract.new([contructorParam1] [, contructorParam2], {data: '0x12345...', from: myAccount, gas: 1000000});

After you can do smth like

contractInstance.methodWhichIsDescribedInContract(foo,bar)

So basically all erc20 standart contract must implements methods for sending and receiving tokens so far . But if contract already has the interface why people use raw transactions ?

1) Is it possible to interact with blockchain without contract ?

2) Is it the case for using raw transaction ?

3) If we have smart contract does it mean we don't need raw transactions?

Thanks

Edit 1 Example of raw transaction

var tx = new ethereumjs.Tx({
  nonce: nonce,
  gasPrice: web3.toHex(web3.toWei('20', 'gwei')),
  gasLimit: 100000,
  to: address,
  value: 0,
  data: data,
});
tx.sign(ethereumjs.Buffer.Buffer.from(privateKey, 'hex'));

var raw = '0x' + tx.serialize().toString('hex');
web3.eth.sendRawTransaction(raw, function (err, transactionHash) {
  console.log(transactionHash);
});

Answer 1

Q1. Yes. You can, of course, use the native protocol which even includes simple ether transfers. You can also send raw transactions.

Q2. mmmm ... I would prefer to use ABI whenever possible, and it's always possible if you have the contract source. That leaves a fairly narrow band of situation, One such situation might be the idea of a general-purpose wallet that will let people send arbitrary data to arbitrary addresses without validating that the raw data makes sense in the context of the contract on the other side.

Q3. Generally, Yes. Especially in the case that you move up to a higher level of abstraction such as Truffle, then the preferred mode would be interacting with the well-delineated contract ABI and letting the tools construct the low-level interface for you.

Hope it helps.