Set Exploration Point feature gives free line of sight to unreachable areas

It appears that if your villager’s cant reach an area that is targeted by the Set Exploration Point flags then you will receive free visibility of the area.

See below example image with map revealed as my villagers cant leave the island.
https://imgur.com/a/6zRoqgZ
This was on Ver: v1.1.0
Seed is - 63D41D25B26

This is by design.

Usually when targeting an area in the middle of a lake. It’s oddly helpful if you know the lake is huge and want to get some cheap/easy views in.