You're forgetting that USB-PD is also 15V. But even if we agree to also ditch 15V, limiting ourself to 60W max, how many amps can those selector chips handle? If they are doing the job of switching between voltage planes they also need to be capable of handling the maximum current passing through them. I kind of doubt a $1 chip is built to handle 5A or more continuously , but I could of course be wrong. (Also remember it can't just be a dumb PD negotiation chip, it also needs to handle passing through at least 10GBPs data and USB alt modes like DP). I've used a few of those dirt cheap PD receiver boards for DIY projects (so handy! And so cheap!), but those don't work for data transfer, just negotiate power delivery, so you'd need a much more advanced chip than that. Also, where would the extra voltage plane go on today's crowded motherboards? Remember, even a single added layer can drive up board costs dramatically. And remember how competitive the motherboard market is - even saving a dollar or two on the BOM is worth a lot to manufacturers. Not to mention that even ATX boards these days are stuffed to the gills, which will only get worse with DDR5 and PCIe 4.0/5.0. Fitting another voltage plane capable of handling a handful of amps, one or more powerful voltage regulators and a selector chip per port? All behind the rear I/O, where the CPU VRM usually lives? That sounds both expensive and very cramped. Would probably work well for a couple of ports on an add-in card like the one you shared, but it won't become standard any time soon. Also, any standard feature would need to scale down to ITX size, which... well, just no. Not happening.