Froome was past his peak though and crashed heavily in a hard Giro. Contador was in his peak in 2011, but that Giro was probably the hardest ever and was hampered by crashes in the Tour while having very weak team in both races.Both Contador and Froome tried it. Both were the dominant GT riders in the peloton at the time. But the other thing we are forgetting is the gap between Pogacar and the rest of the peloton. Think about the manner of his wins after the Tour and the fact he had been winning since March (Strade Bianche) with an 81km breakaway. Neither Contador nor Froome did anything remotely close.
I have very little doubt that peak Froome could do it if the competition in the Giro was so weak and Quintana was injured.
I'm sure Contador could do it as well in the conditions Pogacar had.
They certainly wouldn't dominate both GT's the way Pogacar did though.