Why ARE there brilliant moves in chess?

Also can a move be a quiet positional move and still a capture and thus a brilliancy, the Rxc3 sacrifice in the sicilian is often considered a brilliant sacrifice with no immediate payoff, and is relatively quiet but it is a capture

https://www.chessgames.com/perl/chessgame?gid=1848607
It is just checkmate in 2.

I do note even consider 30...Qxh3+ as brilliant
https://www.chessgames.com/perl/chessgame?gid=1084375

"Rxc3 sacrifice in the sicilian"

• It is thematic. Each Sicilian player looks at it. Nothing brilliant about ...Rxc3.

@tpr said ^

I do note even consider 30...Qxh3+ as brilliant
https://www.chessgames.com/perl/chessgame?gid=1084375

Wow you must have extremely high standards for a brilliancy then, what would count as a brilliancy then?

"what would count as a brilliancy then?"

• Any move that satisfies all 4 criteria.
  I gave an example above: Botvinnik-Capablanca 1938: 30 Ba3
  https://www.chessgames.com/perl/chessgame?gid=1031957
  'It was a pleasure to lose to Botvinnik, he played so well. He misled me completely.
  I thought I was winning. Very clever ! Very good!' - Capablanca

@tpr said ^

"what would count as a brilliancy then?"

• Any move that satisfies all 4 criteria.
  I gave an example above: Botvinnik-Capablanca 1938: 30 Ba3
  https://www.chessgames.com/perl/chessgame?gid=1031957
  'It was a pleasure to lose to Botvinnik, he played so well. He misled me completely.
  I thought I was winning. Very clever ! Very good!' - Capablanca

Weird question from me, would you have considered that move a brilliancy if there was a pawn on a3

"would you have considered that move a brilliancy if there was a pawn on a3"

• No.

@tpr said ^

"would you have considered that move a brilliancy if there was a pawn on a3"

• No.

That's funny to me because the exact idea is the same, both moves are counter-intuitive, and both would be the only winning move, but you discount it as brilliant because it is a capture and solely because of that

"the exact idea is the same"

• Would you consider Bxa3 brilliant if a knight, bishop, rook, or queen were on a3? The exact idea is the same.

@tpr said ^

"the exact idea is the same"

• Would you consider Bxa3 brilliant if a knight, bishop, rook, or queen were on a3? The exact idea is the same.

No but in that case it is also a gain or trade of material rather than a sacrifice of it, it makes the move intuitive rather than unintuitive so it is no longer brilliant, with a pawn there, the move still meets all other criteria, so i'm curious as to see why it doesn't work as one then, I will say, it is more brilliant without a hypothetical pawn on a3, but I would still count it as brilliant nonetheless, maybe i'm just not good enough at chess to understand what a brilliant move actually is lol.