I've created an account here just to post about this, mostly to clarify a couple things:

1. You can continue to use your USB-C power bricks without issue, unless the voltage doesn't match up. USB-C Power Delivery (PD) is a different spec from what Nintendo uses with the docks.

2. Nintendo isn't likely trying to be nefarious here. USB-C is a pretty complex technology. When you plug in a USB-C dongle into a device, the device has to determine what said dongle is. It's basically doing a "handshake" with the device to find out if it's acting as HDMI, power, USB, ethernet, etc. When you put your Switch in the dock, it quickly identifies the dock as "HDMI with Power Delivery." It also identifies the order this should happen in: i.e., the Switch dock could be recognized as an HDMI port, with power second, with USB ports third. AFAIK, there is no way for Nintendo to give their dock an advantage here.

That being said, USB-C as a spec is complicated, because it's a spec that represents all the different specs for HDMI, power, USB, etc., all over the world, and all at once. If you make a USB-C dock or dongle, you really need to know what you're doing. If you mess up, you'll — you guessed it — damage the device after you plug in said peripheral.

I'm guessing that Nintendo wanted to prevent crappy USB-C stuff from damaging consoles, and tightened up what was "okay" to use via the 5.0 software update. That ironically bricked a ton of devices using USB-C devices made by companies who don't know what they're doing. Nintendo looks like they're to blame, but in reality, your Switch could have potentially been bricked by those devices one day regardless.

I don't know anything about what's going on at Nintendo, but they do have to program the Switch to recognize the dock in a certain order. So, in other words, if they changed it from the Switch dock being an HDMI port first, power second, USB third, to a different hub stack, then that would be enough for any differing third party dock that operates differently to brick your console.

The reason that USB-C power banks and chargers are still fine is because the Switch doesn't have to know the sequential order of the bank's features. The power bank isn't a hub; it's just power. So those of you who plug your Switch into an iPad charger are fine.