Solidity ABI – Why Use ABI Encoding/Decoding for Method Parameters

I have seen source codes where they would encode a bunch of parameters into a single bytes parameter and pass it into a function, what's the real purpose of doing it? For example:

function hello(bytes memory data) public {
  (string memory name, uint256 age) = abi.decode(data, (string, uint));
  // do something with name and age
}

In the example above, both name and age can be passed into hello() function as a single parameter data. But within the function, I will still have to know how to decode data, which means that I already know beforehand what will be passed into this function. Then, why even use encode/decode and not just like this:

function hello(string name, uint256 age) public {
  // do something with name and age
}

Isn't it more straightforward to simply separate the parameters in the method arguments than having to decode it later? In fact, as a client interacting with this contract, I don't have to go through the trouble of encoding the parameters; I can just easily pass the values into the method!

What's the benefits of using abi encoding/decoding compared to just separating the arguments? In what scenario should I consider using the abi encoding/decoding method over separate the arguments in a function? What should be the best practice?