First of all, I said UNTIL 1970 United were the bigger club. Both Everton and United had already won 7 league titles before that, but United's way of producing young, vibrant teams, their success in Europe, along with the tragedies meant that United were the bigger side. The philosophy and the style that Sir Matt Busby had regarding youth, was unprecedented at the time. It changed English football and probably the world. Real were winning with mercenaries like Di Stefano and Puskas, but we attempted to win by our Busby Babes, just the Munich tragedy stopped us.
Massive clubs help having a very good national team. Barcelona's and Real's success made Spain great. Bayern's and Ajax's success in 70s made Germany and Holland great respectively. Your greatest English player, Charlton, came from united. He made England the champions. United's success would make England great. Won't you like England to be successful?
As for your demise, your fault is not having a continuous plan like Liverpool and we had. Both the clubs never got tired of success, we kept on planning to continue success. Your club is to be blamed not to have the plans, like making your stadium bigger, to continue success during the 80s. No body can be blamed for such lack of long term vision.