The primary goal of this announcement isn't that Zen 3 is better than Zen 2, the goal is to show that AMD/Zen 3 is better than Intel. Zen 2 is already better at nearly all workloads, with the only exception being gaming.
They could focus on compilation benchmarks, content creation benchmarks, etc. But the people who care about those benchmarks are already going to be buying whatever the latest AMD CPU is in their segment. The only people who are going to sit down and say, "hmm, should I buy an AMD or Intel CPU?" are gamers. So that's where they're focusing their marketing budget.
They could focus on compilation benchmarks, content creation benchmarks, etc. But the people who care about those benchmarks are already going to be buying whatever the latest AMD CPU is in their segment. The only people who are going to sit down and say, "hmm, should I buy an AMD or Intel CPU?" are gamers. So that's where they're focusing their marketing budget.