The Magpies have been heavily criticised by the club’s fans for fielding a weakened line-up when his side were held 1-1 at home by Blackburn in the third round.
Newcastle, who face Rovers in the replay at Ewood Park on Tuesday, slipped into the Premier League’s bottom three at the weekend after losing 2-1 at Chelsea.
“We can talk about ‘oh the cups’, but a lot of teams went out of the FA Cup. Why?” Benitez said.
“Why are all the managers that were making decisions and their teams were having problems and they are out?
“Why Cardiff, Fulham, nearly Southampton, why you see these teams and they were out? Because the Premier League is massive.
“You have £130m guaranteed if you are there. So everyone is trying to manage the situation. Also, you have to be realistic.
“Who has a chance, a realistic chance? Teams in the middle of the table because they can have a go because they are safe. The other teams, you have to manage it really carefully.”
Benitez cited the injury sustained by Jonjo Shelvey against Blackburn.
Shelvey missed out at Stamford Bridge due to a calf strain, while Benitez is also without fellow midfielders Mo Diame (hip) and Ki Sung-yueng, who is at the Asian Cup with South Korea.
“Listen, Jonjo Shelvey was playing the other day because we were trying to change and then win the game and avoid the replay – and he is injured now.
“What does that mean for us, with Ki away, with Muto (Yoshinoro) away? It is a risk. It is not that you have one week and you can recover the players.
“It is a risk and you have to accept that it is a risk. After, you approach the game in one way or another way.
“But if you put this player in or the other one, maybe it doesn’t change anything, and then you take a massive risk.”