Is USB-C Chasing an Unachievable Goal?

There’s an old XKCD comic that brilliantly captures the difficulty of creating a single unified standard to control all device interactions or capabilities. It’s not an entirely impossible goal–USB-A has dominated the market for keyboards, mice, thumb drives, and a number of other peripherals for many years–but the larger the scope of the project, the more difficult it is to bring every device under the same roof.

In a recent blog post, Marco Arment–whose work we’ve covered in various articles before–argues USB-C is effectively chasing an impossible dream with its starry-eyed goal of unifying virtually every other standard into a single diminutive cable. And based on what we’ve seen in the market just so far, he’s got a point.

Comic by xkcd

When Intel announced USB-C would carry Thunderbolt 3, it seemed like a great match-up. USB-C had already positioned itself as a cable and plug standard capable of carrying everything from power to video, and Thunderbolt 3 had bandwidth and low-latency operation capabilities that no other standard has yet matched. But the reality of USB-C (USB Type-C if we’re being technically correct) is that the various cable standards have created a nightmare of cables and products with widely varying compatibility and capability, all wrapped up in the same physical cables. If having to buy a bunch of standard-specific cables is bad, needing a bunch of standard-specific cables that all look identical is worse. As Arment writes:

USB-C normally transfers data by the USB protocol, but it also supports Thunderbolt… sometimes. The 12-inch MacBook has a USB-C port, but it doesn’t support Thunderbolt at all. All other modern MacBook models support Thunderbolt over their USB-C ports… but if you have a 13-inch model, and it has a Touch Bar, then the right-side ports don’t have full Thunderbolt bandwidth.

If you bought a USB-C cable, it might support Thunderbolt, or it might not. There’s no way to tell by looking at it… While a wide variety of USB-C dongles are available, most use the same handful of unreliable, mediocre chips inside. Some USB-A dongles make Wi-Fi drop on MacBook Pros. Some USB-A devices don’t work properly when adapted to USB-C, or only work in certain ports. Some devices only work when plugged directly into a laptop’s precious few USB-C ports, rather than any hubs or dongles. And reliable HDMI output seems nearly impossible in practice.

Issues like this are why Google Pixel engineer Benson Leung created his own database of cables he’d tested, to determine which of them were compatible with USB-C as properly implemented and which were not. The amount of publicity his efforts earned, and the occasionally cataclysmic failure of the products he tested, weren’t unusual but par for the course. The central problem is this: There are an enormous number of types of USB-C cables, and their capabilities and features aren’t stacked directly on top of one another.

Before USB-C, backwards compatibility was much simpler. There were certain edge cases–a device that used USB 3.0 for power, for example, might need a compatible cable and a genuine USB 3.0 port, though a handful of devices with USB 2.0 ports delivered power to them via a specific “high power” port. But with USB-C, your cable might support power delivery, but not Thunderbolt. It might support USB Type-C, but not USB 3.1. There are four different Alternate Modes: HDMI, DisplayPort, MHL, and Thunderbolt, and a cable supporting one of them doesn’t mean it supports the others. There’s a matrix on Wikipedia that shows the differences:

Courtesy of Wikipedia

That’s just for cables that support Alternate Modes, mind you–and not all do. As Arment details, compatibility between different products and standards ranges from functional to terrible.

Too Many Cooks in the Kitchen

Every standard has to strike a balance between price, capability, and flexibility. In theory, the USB-IF could’ve mandated one USB-C standard in which every single feature was supported at every level. The problem with this option is that it would’ve kept cable prices high.

Building a USB-C cable that can handle delivering up to 100W of power and supports Thunderbolt 3 is more expensive than a cable that supports USB 2.0 transfer speeds and charging via USB-C. Cable lengths would have had to be much shorter, since delivering that kind of capability over a long wire is much more difficult than the USB 2.0 option. And taking a step like this would’ve made it much less likely companies would adopt the standard, since few mobile phones ship with USB 3.0 chipsets (for example), and companies would’ve been much less interested in being forced to use a solution that consumes much more power than traditional USB. Being forced to bundle a cable with a bunch of support for features your phone doesn’t use isn’t going to win OEM support, either.

But therein lies the problem. In this case, the flexibility of USB-C actually makes it less likely that we’ll see the port take over everything. It’s confusing, it’s vastly more complex than any previous USB standard, and it’s not doing consumers any particular favors.