According to Stockfish, chess would be more equal without castling. (+0.4 w/castling enabled, +0.1 w/o castling) : r/chess

Dissecting Stockfish Part 2: In-Depth Look at a chess engine, by Antoine Champion

stockfish - How many moves out do the static board evaluations use? - Chess Stack Exchange

combinatorics - k non-attacking rooks on a chessboard with forbidden positions - Mathematics Stack Exchange

Stockfish 16 vs Chess.com Maximum

First-move advantage in chess - Wikipedia

No-Castle Chess is Flawed. No-castle chess is flawed. Castling was…, by Tony Berard, Board Games and Cards

Stockfish 16 (4.2K Elo) Played an Epic Chess Game with Magnus Carlsen without Rook, Chess

rules - How is white allowed to castle 0-0-0 in this position? - Chess Stack Exchange

Stockfish 16 vs Chess.com [Maximum (3200) Level 25]

Why is Stockfish better than other chess engines? - Quora

Is it true that no one (not even Magnus Carlsen) can beat Stockfish at chess? - Quora

Is castling in chess possible when the king is in check and there are no moves left without castling? - Quora

Stockfish (chess) - Wikipedia

Castling without a rook - Chess Forums