Ancelotti may think that Marco Asensio, Rodrygo Goes, Federico Valverde can always be relied upon throughout the season so that he can keep his team's performance good. But in fact not, as a result every time Benzema is injured, Real Madrid really has a hard time getting the most out of the match.
It is not what Ancelotti and Real Madrid thought. They only well prepared for days when Benzema and other old players will be no longer able to play for them. Vini Jr., Rodrgyo, Valverde, Camavinga, Tchouameni were bought for their plan.
Asensio can not upgrade himself and I believe he already touched his best, Real Madrid must satisfy with what he can contribute or sell him to another club and get money. For other young players, they have potential to grow up more and upgrade themselves.
I agree that in this season, Rodrygo is still a young player and has lot of things to learn. Vini, Rodrygo are not able to replace Benzema at the moment but they are doing well and in future, they will become important players of Real Madrid.
Benzema impacts Real Madrid performance a lot because his contribution is not only by scoring goals but by his moment, attraction to opponent defenders and his ability to make good passes as well as assists.
Another big problem that Real Madrid might really feel if Benzema and Vinicius were injured at the same time. Obviously that will make Real Madrid's attack line weaker and it's likely they won't be able to win many match ahead. But Vinicius is still fit enough to rely on, but Rodrygo, Valverde or Asensio are not entirely reliable as the main line-up.
Having multiple players on hospitals, in medical care process is bad for all clubs, not only for Real Madrid. It is one of risks they have but such situations won't occur too often. In addition, last few seasons, I did not see Real Madrid had many problems with massive injuries on their players. It can be contributed by their medical staffs and because in previous seasons, many players were younger than now.