I can see the appeal. I like a beer, I very much enjoy watching (for example) the cricket with a beer in hand. I could imagine enjoying watching United with a beer in hand.
But it's a very different kettle of fish. The only time you really get (I fucking despise this concept) "limbs" at cricket is at the end of a match, when losing your last half pint doesn't really matter. At football, you'd get the dickhead instagram wankers launching their pints into the air when someone got a corner, or made a robust tackle. It would be a fucking mess. You also get silly cunts who launch themselves onto you from the row behind at the slightest provocation. Good fun for a last minute winner in a tight, important game. Less enjoyable when it's cos you've gone 2-0 up against Halifax in the League cup.
Overall, and I genuinely surprise myself saying this, as I thought it's something I'd have wanted, I'd probably be against it. I can (and do) have a few pints before and after a match, without the risk of some twat launching a pint of warm, crap lager over my head, or knocking my own pint of warm, crap, overpriced lager out of my hands when I've just paid the GDP of a small country for it.