I am looking at buying a house. Today I looked at a house and when I looked under the kitchen sink the drain was disconnected and routed through the outside wall, right into the yard? The washing machine drain is the same way? Why would someone do that? The toilets and bathroom sinks are not that way.

The logical answer is to keep using those items because they have a clog/blockage they could not clear.

Maybe it didn't affect any other drain.