Sicilian endgames - favourable for which side and why?

Question

I often come across statements like this:

Generally speaking, Sicilian endgames tend to favour Black for structural reasons. The extra center pawn and the half-open c-file are both advantageous for the second the player.

This is surprising to me, as I've also read that queenside pawn majorities are good in the endgame (e.g. in papers about the Grünfeld defence). I thought that the central pawn majority would rather give Black an advantage in the middle game, because there are still more pieces that need to be actively placed near the center. The queenside pawn majority however entails the potential to create a passed pawn that is more remote than the passed pawn that Black would be able to create using his majority. Why would the endgames be good for Black in the Grünfeld, but not for White in the Sicilian? If Black's central pawn majority in the center is advantageous during the middle game and the endgame, why isn't the Sicilian not just better for Black (after White's initial initiative has been fended off)?

Answer 1

The extra center pawn

The first basic endgame principle that beginners are taught is that when there are pawns on both sides of the board their first general priority is to centralize the king. If you control the center then that is much easier for you to do than for your opponent. In the endgame, with most of the pieces gone, it is easier for black to move the normally backward central pawns forward and establish control of the center.

the half-open c-file

If rooks are on the board, which they are in the majority of endgames, then a half-open c-file gives you a natural target for your rook(s). A common theme here is to combine this pressure with a minority attack - advancing the a and b pawns to undermine white's pawn support for the c pawn after it is advanced.

If Black's central pawn majority in the center is advantageous during the middle game and the endgame, why isn't the Sicilian not just better for Black

You control the center with pawns by having pawns on the key central squares - c4/5, d4/5, e4/5, f4/5. If white has pawns on e4 and possibly f4 and black's central pawns are no further forward than the 3rd rank then it is white who has more control of the center and an advantage, not black.

Answer 2

Between the Sicilian opening and the Sicilian ending the gods have placed the Sicilian middlegame.

During that period, Black is opening lines and activating pieces on the Queens side, conducting a sort of minority attack. If Black were to play passively your conclusion would be correct. Therefore, he must not play passively.