Quote: 'all rook endgames are drawn', 'All rook endings are drawn' or 'All rook and pawn endings are drawn.'
For queen endgames, Karsten Müller even gives a way of visualising this (not quite Karsten Müller's point or intention, but at least the ff is my interpretation): Imagine some arbitrary queen endgame or rook endgame and then imagine the queens are replaced with rooks or vice-versa. 1 example was for a position involving queen and 2 pawns vs queen. Karsten Müller points out that the position was drawn but then it's not drawn for if the queens were replaced with rooks.
For opposite coloured bishop endgames (eg this recent question), Josh Waitzkin gives examples how they are so drawish. Even in my own games, this is the easiest kind of endgame to see its (insane) drawish tendency. I absolutely do not see queen endgames or rook endgames on the same level as opposite coloured bishop endgames.
Question: What's the idea of 'all rook endgames are drawn' ?
I suppose even though opposite coloured bishop endgames are like superGM level in terms of drawish tendencies doesn't mean rook endgames can't be IM level or even GM level (like rook endgames are 90% drawish vs queen endgames or opposite coloured bishop endgames are 99% drawish?).
Perhaps the idea of the quote is that it's difficult to convert a 1 pawn advantage (or that 1 pawn isn't much of an advantage. or is it?) in rook endgames, but then the difficulty here doesn't mean there aren't more difficult endgames to win (eg 2 pawns up in either queen endgame or opposite coloured bishop endgame).
Attempt of answering the question by statistics:
Are there any statistics or something to show how drawish rook endgames are? Otherwise I guess the answer to this post is gonna be just
The context of this quote shows it is a comment on the fact that a small advantage in a rook and pawn endgame is less likely to be converted into a win.