There were no usages of more than one column being provided per row, so
it seemed like unnecessarily complexity. I'm currently trying to reduce
complexity so we can improve the layout of the results screen, which
currently has up to three levels of nested `GridContainer`s.
Of note, I can't add backwards compatibility because the method
signature has not changed in `Ruleset` (only the return type). If we do
want to keep compatibility with other rulesets, we could designate a new
name for the updated method.
