Looking for some clarification on why my if statement isn't working

I am attempting a challenge on codewars as follows:

Story

YouTube had a like and a dislike button, which allowed users to express their opinions about particular content. It was set up in such a way that you cannot like and dislike a video at the same time.

There are two other interesting rules to be noted about the interface: Pressing a button, which is already active, will undo your press. If you press the like button after pressing the dislike button, the like button overwrites the previous "Dislike" state. The same is true for the other way round.

Task

Create a function that takes in a list of button inputs and returns the final state.

Examples

likeOrDislike([Dislike]) => Dislike
likeOrDislike([Like, Like]) => Nothing
likeOrDislike([Dislike, Like]) => Like
likeOrDislike([Like, Dislike, Dislike]) => Nothing

Notes

If no button is currently active, return Nothing.
If the list is empty, return Nothing

I was stuck trying mutliple different ways to solve it for a couple of hours before checking the solutions and found one very similar to mine, albeit with one difference.

My code is as follows:

function likeOrDislike(buttons) {
  let answer = 'Nothing';

  for (let i = 0; i < buttons.length; i++) {
    if (buttons[i] !== 'Nothing') {
      answer = buttons[i];
    }
  }

  return answer;
}

Working solution below:

function likeOrDislike(buttons) {
  let state = 'Nothing';

  for (let i = 0; i < buttons.length; i++) {
    if (buttons[i] === state) {
      state = 'Nothing';
    } else {
      state = buttons[i];
    }
  }

  return state;
}

So it's pretty much the same method used to solve it, however I don't understand why in the working solution, you have to declare the variable 'state' as 'Nothing' again when it's already been declared outside the loop.

I thought that I could just create one condition for if buttons[i] is not equal to 'Nothing' and then assumed it it would default to 'Nothing' in any other case since it was declared outside of the loop.

'reduce' is perfect for this situation. If the same button is pressed twice, you get Nothing. Otherwise, the button pressed is the new state.

<!-- begin snippet: js hide: false console: true babel: false -->

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const [Nothing, Like, Dislike] = ['Nothing', 'Like', 'Dislike']

function likeOrDislike(seq) {
  return seq.reduce((a,c) => a===c ? Nothing : c, Nothing)
}

console.log(likeOrDislike([Dislike])) // Dislike
console.log(likeOrDislike([Like, Like])) // Nothing
console.log(likeOrDislike([Dislike, Like])) // Like
console.log(likeOrDislike([Like, Dislike, Dislike])) // Nothing

<!-- end snippet -->