Anyway, maybe all of the goals could have been prevented, maybe none of them.
If Ronaldo did more, it would make it easier for Real to maintain a compact shape and deny opponents space in key areas.
Just now, either the left-back is exposed or the midfield has to cover a lot of ground on that side of the pitch.
Those things create more space for teams to play through the middle of Real and also leave their CBs more space to cover.
In an ideal scenario, Real would have the defence and midfield that would allow them to leave Ronaldo with no responsibility, but they don't have that, so need all the help they can get to maintain a proper structure and help to mask the weaknesses in the middle of their team.