Earlier quoted context omitted.
There was some dock from a 3rd party vendor that let you do more screens, but I can't remember which one...
There are a few. They are able to do this by using something called Display Stream Compression. While it may be find for some, a lot of us would prefer not to have a diminished experience with a compressed stream.
Instead, those docks use a technology called DisplayLink which has nothing to do with DSC. DisplayLink means that external monitors are basically "software" displays that are tremendously slower and often very limited in resolutions and frame rates. Having any DisplayLink display connected also breaks HDCP and can cause other problems.