but don't mix it up with the cable for the LG 4k display because that only supports 60W and isn't a thunderbolt cable, because the way the 4k display works (USB-C/DisplayPort alt mode) is completely different to the 5k (2 DisplayPort channels tunnelled over a Thunderbolt link) so neither cable will drive the other display (although a 0.5m passive Thunderbolt 3 cable might).
The standard is for both USB and Thunderbolt 3 USB-C cables. Currently nearly all of the USB-C cabling (be it for USB, be it for Thunderbolt 3) support 60W max. The cable included with the LG 5k display and those from CalDigit are currently the only exceptions as they support up to 100W.
See for more info, page 27 of the following pdf document:
Universal Serial Bus Type-C Cable and Connector Specification (rev 1.2).
So, yeah, a single cable for everything... sorry, but, between them, the USB Consortium and Intel have already wrecked that dream.
They didn't. Take a closer look.
Or are machines like the Dell XPS 13, the HP Spectre 3560, the Asus Transformer Pro, Razer Blade Stealth and many of the other machines listed here that claim to have both USB A ports and Thunderbolt 3 part of some great fake news conspiracy? The standard intel processor chipset provided a bunch of USB 2 and USB 3 ports as standard.
Nope, they are running into the very same issue. The USB-C ports (or port because mostly it is only 1 port) on their machines are linked to the Thunderbolt 3 controller or, like the MacBook, to the USB controller in the CPU (which means there is no Thunderbolt 3 on the machine).
They simply made a different choice than Apple did and used just 1 Thunderbolt 3 controller and only 1 port of that controller. Everything else goes through other ports. They have simply distributed the available controllers and PCIe lanes differently as they found the compromises to be acceptable and because they simply had far more PCIe lanes to use.
You are forgetting the issue with the Thunderbolt 3 ports on the righthand side of the 13" MBP Touch Bar. These are slower than the left ones due to insufficient PCIe lanes.
A lot of PC motherboards are turning up with 1xTB3 and 1 x red USB A 3.1gen2 socket (which I believe is one way of configuring the TB controller chip).
They are more likely to be using a separate USB 3.1 Gen 2 controller (although you can indeed do this with the TB controller by configuring 1 port for TB and the other for USB) and they can since they are big ATX motherboards where you have far more space for all these things than on one for a notebook.
Now, whether you could have four TB3 ports and still have enough i/o bandwidth to provide a couple of USB3.1 ports is a question, but who asked for four of the things - particularly at the expense of anything else?
The pros did because now they get 4x 40Gbps and they can now choose their own ports instead of Apple choosing it for them. All ports now do USB, ethernet, Thunderbolt, DisplayPort, DVI/HDMI, VGA and power. Before you could only do USB or Thunderbolt + DisplayPort, DVI/HDMI and VGA or ethernet or power. Basically if you used more than 2 USB devices you had to bring a hub because you could only connect 2 of them.
The 13" can't drive all of those at 40Gbps anyway even if the thermally-throttled CPU could deal with all that data.
Not only do the specs at ark.intel.com tell a rather different story so do experiences by users on this forum. The above is simply complete and utter nonsense.
2 x TB3 + 2 x USB 3 (A) would have been a much more convenient setup for many people - especially if (1) there was still a magsafe so you didn't "waste" a TB3 port on power unless you wanted to use a TB3 dock with charging and (2) they hadn't gimped the alt-mode displayport MST support so you couldn't drive 2 displayport monitors off one port without an expensive TB3 hub.
The exact same thing can be said about the current setup: for many people the 4 Thunderbolt 3 ports is a much more convenient setup because it lacks the limitations you have with the 2 Thunderbolt 3, 2 USB-A ports and 1 Mag Safe. Basically it is 4 ports vs 2+2+1 (in case you haven't realised it: because you cannot use all the ports for the same thing you cannot add them up; with Thunderbolt 3 you can, hence the difference).
The part about DisplayPort is complete and utter nonsense. MST is required for the LG 5k display to work and this display has 1 Thunderbolt 3 port on it and thus completely invalidates your point. This display shows that you can run an MST display from 1 port. The feature you mean is called DisplayPort daisy chaining and it is also fully supported by Thunderbolt 3 (but it is not a Thunderbolt thing, it is part of the DisplayPort standard). The display/graphical driver in macOS is the one to blame here because this one doesn't support DisplayPort daisy chaining. And even that isn't exactly correct because the second display will work. The issue here is that the second display will be a mirror of the first. You cannot extend your desktop to that second display. Someone reviewing the HP TB3 dock
found the same thing. This has been known every since DisplayPort 1.2 came to market!
With Thunderbolt supporting daisy chaining as well you can use that to connect a max of 6 devices to 1 port where a display can be put at the end if it doesn't support Thunderbolt but DisplayPort (or DVI/HDMI or VGA) instead. With 4 Thunderbolt 3 ports you actually have 4 ports available. With the GPU in the 15" model you can actually drive 6 displays (incl. the internal display so when using that you only have 5 left), the iGPU can't. Or you can use a dock (a hub is something rather different) to inject another set of 2 DisplayPort streams.
TL;DR: you need to work on your reading comprehension and start learning about Thunderbolt 3 as your knowledge is extremely limited. You seem to be basing everything on hear-say instead of the
official documentation and the experiences by people on this forum as well as those in others aimed at eGPUs.
