I don't think anyone buys new hardware based on emulation, just like people don't buy new consoles for bc even though it may seem like a solid bullet point.
It's a plus, and yes before necrokiller chimes in, I have done a fair share of emulation on my pc (including BoTW on the WiiU emulator) but it's far from the primary reason to upgrade.
In a world where people upgrade their PCs for benchmarking and bragging rights, upgrading for better emulation performance is amongst the less crazy things.
I didn't say that it's the primary reason to upgrade (although for some people it can be). But when upgrading, performance of emulation can play a part in deciding which part to buy. For example when buying new processor, if processor costing $200 is adequate for all processing requirements for official work as well as for PC gaming, better emulation performance may push a person towards the processor costing $230 or $250. Or it may be the deciding factor between going with Intel or AMD processor (was more of a factor before new gen Ryzen).
Similarly, before recent improvements in Vulkan API performance, Nvidia GPUs performed better than AMD GPUs for Cemu (OpenGL). So if GPUs from AMD and Nvidia performed similarly and were priced close to each other, anybody caring for better emulation performance used to prefer Nvidia due to this additional advantage.