Mourinho wanted to win major trophies everywhere though before he settled. Hardly a bad thing, an ambitious manager who wanted to go down in history. He left Chelsea the first time because abramovich forced him out as well. Not the same thing.
So because Everton isn't owned by Arab or rich owners, that makes it acceptable for a club of their size to have own nothing and not even looking like they will for the last 11 years? I thought you said longevity equals success though? Didn't seem to do much for Everton other then keep them mid table for a decade, and only now with him gone are they looking like moving to the next level. And that's only results wise, ignoring that the overall play is worlds apart. How did they get there? By bringing in a manager who always showed signs of being a very good manager. Having even a shite team like Wigan play good football and win the fa cup, beating moyes' Everton 3-0 in the process.
United is a top club, and so needs to have a top manager in charge, not some average manager. What happens to top clubs when they bring in mid table managers? They go through shit seasons that are labeled as transition years and only when they bring in a top manager do they get back to where they belong, at the top. It's not rocket science really.