I'm trying to find some logic to it.

It does not drain to a (easily) visible location.
It uses up a bunch of copper.
Can't tell if the copper in the wall runs uphill, downhill or loop-d-loops. (interestingly enough the direction the final end of this drain would point at the WH if they were on the same level - about 270deg worth of turns)

There is a floor drain in the room with the WH. Seems it wold be simpler (and safer) to terminate it there.

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