Well if Nintendo didn't purposely set out to make life difficult for people with third party docks is there some other reason this is happening. Have they updated the firmware so that the Switch runs faster and draws more power or some other performance change, faster charging or something?
I don't have a Switch but intend to buy one at some point and will be looking to share one switch console with a dock both downstairs and upstairs, the Nintendo dock seems grossly overpriced for what it is.
Well if you read Shiken's response on the non standard usb-c requirements Nintendo used to safely charge and not damage the console, perhaps they added some checks to ensure the dock stays in those limits. So any dock outside spec will not work and dock within spec will as indicated not all 3rd party docks have stopped working. To me that is reasonable approach to take to protect the Switch.
Is that the facts of the situation or are some third party docks not currently recognised as third party currently and may get caught as Nintendo fine tune their dock checking routines in a future firmware? I have a long history with using Nintendo products dating back to the NES and they are quite aggressive to third parties even those that assist them commercially. Sony with their SNES CDROM add-on, developers of the SFX chip and numerous other companies. They have a very aggressive approach when it comes to their commercial interests. There is huge money in selling their own docks. There is absolutely nothing of value in the dock, a simple circuit board, some plastic and a PSU. Only a few dollars to make surely.