your eye needs somewhere to rest
There is a big difference between newspaper columns and web whitespace. The former are more or less uniform and easily seen (I’ve also read newspapers with explicit delineation of separate articles, and it was even better experience). The latter is just chaotic blobs of whitespace, which doesn’t usually even delineate or makes your eyes rest, it makes them lost instead. You can’t see structure, because it is so blobby. Whitespace should only surround the elements which are much more dense and “thicker” than it. Otherwise it will blend into them dissolving any structure.