Re: Q: Why no PCIe ASIC miners?

Agree with OP.
An PCIe ASIC card would be sick, I would buy for sure.

Let's assume that Chinese engineers can take one of the boards with ASIC chips and make it compatible with a PC via a PCIe interface. The ASIC uses powerful fans to cool the chips. Will you turn your PC into a noisy monster?
Such a board will economically lose to ASICs.

None of that applies to using ASICs in a custom system vs using ASICS with a PCie (or USB) interface in a commodity system. ASiCs are ASICs no matter how they are used.

In this I agree with you. ASIC is a standalone device and does not need an additional interface, except for connecting a LAN cable. If we connect some kind of mining device to the motherboard, then it will be an analogue of a video card or FPGA.