===But without an offside rule it wouldn't be "the modern game" any more. I suppose you could call it a "postmodern game - and goalhanging would inevitably be a significant part of it.=====

On the contrary — it's the idiotic offside rule, formed back when the game was new and the only technique was to boot upfield & hope for the best, which is now the most OLD-FASHIONED aspect of the game to survive. Getting rid of it, and so necessitating new defensive techniques to obviate goal-hanging risks, would inevitably enliven & modernise the game.