The whole "move to another team" argument has never made sense. Ever. For so many reasons.
Pele, Maradona, Cruyff, none of these guys carried "weak" teams to anything. :S Firstly, given that players run about literally twice as much each match as they did in the 50s, 60s and 70s, its even less possible now than it was then. No-one thinks less of Cruyff because they lost a WC final. No-one thinks less of Pele because he was surrounded by great players at Santos and Brazil. (and several of his "league titles were won over 4-5 games. Seriously, go look it up). No-one thinks less of Maradona for having a comparably small trophy collection for such a vast talent. If anything it's the opposite, the 86 Argentina team was their best ever team, yet legendary names like Bochini, Passarella, Valdano, Ruggeri, Burruchaga etc have been airbrushed as "plumbers" to enhance the legend.
The reality is, given who these debates tend to be focussed on, if you put Messi and Ronaldo in League One level teams, what you will actually see is;
Messi constantly looking for passes and not making any, because teammates wouldn't have the understanding and quickness to make the off the ball decisions, so he would end up trying to force passes to drive the players to run and end up loosing the ball all the time.
Ronaldo constantly trying to make sharp runs to open space and never receiving the ball because the plodders in midfield didn't react quickly enough and didn't have the vision or technique to place the ball, so he would end up being offside 30 times a game and never getting the ball in the right spaces.
La Liga has been, for the whole time these two guys have played, been generally the no.1 ranked league by UEFA, except for a few years where it was no.2. With all due respect, what would moving to Serie A or whatever prove? It's a step down by all metrics, it's not a "challenge" at all. This is the issue with the people who want to use stats for everything. Pure, cold numbers can't tell the full story. Some people might finally see that given that for example Ronaldo did everything he could against Lyon in that game, but Juve still went out. Ronaldo did his part, the others didn't, and now they are out.
Because Higuain will always suck.