Chesterton's point was that, if reformers want to remove a fence from a road, they should only be able to do so if they can explain why it was deemed necessary in the first place.
An idea that's particularly pertinent to the current Trans debate - if Trans activists want unisex toilets etc, they would need to explain why s x-specific toilets were deemed necessary in the first place, which you'd think would make them more open to compromise.
en.m.wikipedia.org/wiki/Wikipedia:Chesterton%27s_fence
(Well I found it interesting anyway).