You are right, I quoted from another post without attribution. Your second point is also correct, ignorance has never stopped science before.
The physics of greenhouses is that the air is heated and the rising warm air is trapped by the glass barrier. This prevents convective cooling that occurs in the atmosphere.
It seems to me that clouds at night act more like a blanket than a greenhouse.
Having lived in Seattle, yes the clouds (water vapor) insulate and keeps Seattle’s climate totally different than montana, Minnesota, Spokane, etc.....plus the proximity to the water influences a moderate climate.
Water Vapor cannot be controlled, hence the Global warmer pick CO2 as the Bad boy of climate.