What do I do if my table gets split between two pages? What about my fancy border around the whole table, can I have it render a full border around each split segment of the table or will it just obnoxiously slice the border at the page break? Where will it decide to split the table, will my multi-line row get split down the middle? Moreover, how do all these properties affect the existing intricate layout mechanisms present in CSS?
I feel like these specifications will create fundamental conflicts in the way CSS handles layout, which will probably be resolved by forbiding the combinations of certain layout models. But that goes against the philosophy of CSS: composability.
CSS complects the ideas of UI layout and text flow with a surprisingly expressive language as a result, but those ideas are not truly compatible and eventually inconsitencies like this will arise. These systems push CSS past its practical limit.