If you and your partner have eight or usually more cards between you in two suits, this is a two-suit fit. Hands with a two-suit fit often produce more tricks than the point count or the law of total tricks suggest.
The combination of good controls and the two-suit fit in the pointed suits means that East-West can expect to make a slam with only 20 HCP between them.
You should try harder than usual to buy the contract when your side has a two-suit fit.