> the DP connector found on graphics cards is pretty common (“standard”)
So are D-sub connectors and HDMI. Should it have those as well? What about S-Video? Composite?
> they weren’t forced to make tradeoffs for other features that are common on high end monitors
They don't sell any products with DisplayPort connectors, nor do I think they've ever done so (certainly not recently). Selling a product with that connector is a commitment on some level to supporting what people plug into it, and as demonstrated by the OP, PCs are not really supported. It's also more engineering effort, but that's probably marginal.
This is a standard connector with cheap cables that adapt it to legacy devices using the DP alternate mode of USB-C. Apple are known for getting rid of legacy connectors. USB-C is a superior technology, it's only a matter of time before it's used for everything, and I appreciate Apple's efforts to hasten that day.