I think a better answer for the intelligent DIYer is to weigh your
situation and act upon it.

We cooled using basement air for a dozen years. I turned the furnace
pilot off for the summer and just opened the bottom of the furnace. We
didn't have lint in the basement, so that wasn't a problem either. A
little hokey, but it worked. I closed up the bottom of the furnace
during heating season, of course! Just don't do anything stupid.

And I agree that once you've sucked the cool air out of the basement, it
becomes almost as warm as the rest of the house, except that the ground
keeps on cooling the basement to some extent.