Henry, Eto'o, and Villa all managed to get 20+goals the seasons where Messi won the Ballon D'or 2009-2012 so to say they were struggling whilst trying to accommodate him is bit of a rash claim, as well as claiming the decay in attacking players due to the responsibility of as you say, 'feeding Messi', when infact that Spanish national side has been going downhill as well considering the main core of the national team pertain to Barca's golden generation. Both Xavi and Iniesta were the focal points and its become blatant that their ability is diminishing. We can't forget the fact that Barca lacked an out and out goal scorer like Villa was until the purchase of Suarez. Pedro, Neymar, and Sanchez do not have those instincts. Ibra wasn't cast aside due to Messi struggling whilst playing with him as the media portrayed it to be, it was down to the simple concept that Ibra did not complement their style of play, at all. Barca do not play with a target man and the amount of times Ibra has ruined their rhythm and attacking transition was apparent to Guardiola, hence his transfer. Argentina's biggest mistake was to continue to play Messi in the hole rather than his usual attacking free flowing self.
)When you consider the variables, control, vision, versatility and the ability to play from deep, natural finishing instincts, as most importantly, consistency, that's what separates Messi from Ronaldo. That's roughly debatable but i agree with you, Ronaldo had to go against the likes of Zidane, Rivaldo, and Figo where as Messi had to go against the likes of C.Ronaldo, Iniesta, and Xavi. All players who will go down as some of the formidable best in their respective countries,