Barrows & Wights is an unabashed "OSR retro-clone" designed for simplicity, with a specific goal of enabling online play. The rules assume the referee and/or players will elaborate on most aspects of play - and are thus presented as bare-bones structures.
From the introduction:
"[I]t is expected that the Referee of [the] game will have additional rules (called house rules) based on the game needs. This is a key part of the charm of the game[.]