> Having grid line 1 come before column 1 makes it feel like the grid lines are substantial and the columns are merely the bounds between grid lines.
Correct. And IIRC the spec doesn't even have columns (they're just referenced to help understanding), just column bounds.
Usually you get a reasonable relationship between zero- and one-indexed views of the same thing. The relationship is normally that the zero-indexed points 0 and 1 form the start and end bounds of the 1st item.
CSS grid numbers columns 1, 2, 3 and also number the the lines around those columns 1,2,3,4. https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Grid_La...
Having grid line 1 come before column 1 makes it feel like the grid lines are substantial and the columns are merely the bounds between grid lines.