That's not necessarily true, I think it'd be extraordinarily difficult to get any modern CPU to be in shippable state while still on A-stepping silicon. AMD is still very efficient managing to ship on B-stepping which is very difficult to do on a CPU.
Intel:
13900K - B0 stepping
12900K - C0 stepping (Intel's first mainstream heterogeneous CPU)
11900K - B0 stepping
AMD:
7950X - B2 stepping
5950X - B0 stepping
3950X - B0 stepping
Nvidia - ruled by Jensen's iron fist and they always ship on A-stepping (also it's easier to ship a GPU on A-stepping compared to a CPU)
RTX 4090 - A1 stepping
RTX 3090 - A1 stepping
RTX 2080 Ti - A1 stepping
GTX 1080 Ti - A1 stepping
AMD may not always ship their lead Zen product on A-step silicon, but they've done it for the follow-ons like their mobile chips. That's a tradeoff they make. By serializing the APUs behind the desktop IP implementations (CPU and graphics), they're able to minimize the risk of bugs an engineering effort needed. The sacrifice is time to market. Still, even when they need a B-step, it's more about bug fixes and extra speed than it is getting a baseline bootable product. Even Intel can do that on A-step.
Intel, by contrast, seems to do everything in parallel, even the similar client dies (e.g. 8+8 vs 6+0 ADL-S). Combine this with poor quality tape outs, and you get far, far more steppings in total. They've just been able to hide that cost until now.
And even if you want to ignore AMD, Apple consistently does A-step PRQs, and with the first IP implementations too. It's all a matter of how much time and effort you're willing to spend on pre-silicon validation.