Multiple columns would be fine if the page scrolled horizontally, or if all the content fit nicely on one screen and didn't need to be scrolled vertically, but having columns with vertical scrolling just breaks how I typically read websites.

Typically when reading something on the web I scroll as I go which means that when I get to the end of column one it's in about the middle of the screen. Now I need to scroll back in the opposite direction because the top of column 2 is now off the screen and then read back down again.

It really breaks the flow of reading.