I agree with everything you've said except the part where you imply Chesterton was wrong to charge the demolition-proposer with a duty to do research. That duty

I agree with everything you've said except the part where you imply Chesterton was wrong to charge the demolition-proposer with a duty to do research. That duty absolutely still also exists. In the situation described, even if people putting up fences have a duty to record why, the time for that to happen is long past and there's no utility in complaining about it. It's natural not to bring it up, especially if you assume that the records do exist in some dusty church or town hall attic.