Comment by wtallis

> I use a Thunderbolt dock because I understand how much data 4k screens push, and how a USB dock won’t cut it.

To elaborate on this point: a USB-C dock that includes display connectivity needs to operate at least some of the high-speed lanes of the USB-C connector in DisplayPort Alternate mode. If you split it with two lanes for DisplayPort and two lanes for USB 3.0 signals, then you have halved the potential display bandwidth.

But it's also valid to use all of the high-speed lanes for the DisplayPort signals, limiting the USB bandwidth to the USB 2.0 signals that are carried over separate wires. This is adequate for connecting a keyboard and mouse, but not ideal if you want the dock to provide 1GbE or plan to do large file transfers to external storage devices connected through the dock.

Thunderbolt doesn't always achieve quite the same video bandwidth as raw DP Alt mode, but it allows both DP data and USB data to be multiplexed over all of the high-speed lanes of the USB-C cable, so you can be using more than half the bandwidth for displays and still have enough left over for USB 3.0.

But I don't think the above particularly matters to your use case, because Apple's hardware doesn't support DisplayPort Multi-Stream Transport so the Thunderbolt dock is the only way to drive multiple monitors from just one of the Mac's Type-C ports.