Why does the Gemara give outlandish explanations for Mishnayos? Part 4

Yesterday's daf (Zevachim 22) has another doozy.

R. Yosi b'Rebbi Chanina states if the Kiyor does not contain enough water to be Mekadesh four Kohanim, it is invalid - "v'Rachatzu Mimenu Moshe v'Aharon u'Vanav."

The Gemara asks a question from the following Baraisa: One may be Mekadesh from any Keli Shares, whether or not it contains a Revi'is of water! (a Reviis is much less then the water needed for 4 people)

Rav Ada bar Acha answers: The case is, the Keli Shares was carved into the Kiyor (so the water comes from the Kiyor, which contains enough water to be Mekadesh four Kohanim).

Really??? The Bariasa is talking about a Kli Shares that was carved into the Kiyor? This is a crazy ukimta which does not provide any novel explanation. What principle is the Baraisa with this ukimta teaching us?

Previous posts:
Why does the Gemara give outlandish explanations for Mishnayos?
Why does the Gemara give outlandish explanations for Mishnayos? A possible explanation
Why does the Gemara give outlandish explanations for Mishnayos? Part 2
Why does the Gemara give outlandish explanations for Mishnayos? Part 3