There would then need to be ladders over most of the surface of the chimney, and with the anchors for the ladder mortared into the chimney, and the whole point

There would then need to be ladders over most of the surface of the chimney, and with the anchors for the ladder mortared into the chimney, and the whole point of climbing the ladder in the first place is to repoint the mortar, you couldn't rely on the anchors being sound.