People have already commented on fractions, there’s a lot of math that is way easier to keep accurate by leaving in fractional form as it goes.

For word problems, done correctly, the math is pointless if you can’t map it to more realistic scenarios. In terms of applying math to the real world, it’s supremely rare that the world just spits out the equation ready for you to solve, the ability to distill a scenario described by prose to a mathemetical solution is critical. Problem is when they are handled incorrectly and have ambiguous solutions or parameters, but dealing with kids’ homework, this is pretty rare, though it’s admittedly utterly infuriating when it comes up.